Distal Femur Fracture ORIF (Isolated, Non-Periprosthetic)

Indication. Most isolated distal femur fractures are treated operatively. Operate for a displaced intra-articular fracture (33-B and 33-C) where the joint surface must be restored, a displaced or unstable extra-articular fracture (33-A) with shortening, angulation or rotation, an open fracture (debridement plus stabilisation), polytrauma / floating knee needing early stabilisation, and failed non-operative management (loss of reduction in a cast or brace). Reserve non-operative care for a truly undisplaced, stable fracture in a low-demand patient who can be reliably braced, or a non-ambulatory patient where surgical risk outweighs benefit (consider palliative bracing). Contraindications to ORIF. Absolute: active infection at the operative site (treat first), and a non-reconstructable articular surface in an elderly low-demand patient — consider distal femoral replacement (arthroplasty) instead. Relative: severe osteoporosis with poor purchase (favours a retrograde nail or augmentation), and massive soft-tissue compromise (staged management with a spanning external fixator first). Goals of fixation — the exam framework. (1) Anatomic reduction of the articular surface with absolute stability (lag screws); (2) restoration of length, alignment and rotation of the metaphysis and diaphysis; (3) relative stability across the metaphyseal zone (bridge plating or a nail, for callus healing); (4) preservation of the soft-tissue envelope and blood supply (biological / MIPO technique); and (5) a construct stable enough for early knee motion but NOT so stiff it prevents callus. Consent for nonunion or delayed union (notably the medial supracondylar nonunion), malunion (valgus, recurvatum, rotation, shortening), infection, knee stiffness and arthrofibrosis, hardware irritation or failure, popliteal neurovascular injury, DVT/PE, and the possible need for revision or bone grafting.

The goal is to restore the articular surface anatomically, bridge the metaphyseal comminution with relative stability, restore length/alignment/rotation, preserve biology, and allow early knee motion. The exposure is laid out as the first steps of the operative sequence below, and the dominant decision is which implant fits the pattern and the patient.

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• The tibial and common peroneal nerves run in the popliteal fossa; the common peroneal nerve courses around the fibular neck (relevant if the limb is malpositioned or over-distracted).
• Perforating branches of the profunda femoris supply the distal femur — preserve the medial soft tissue and periosteum (the biological argument for MIPO). ### Surgical approaches

Alternative — retrograde intramedullary nail Indications. Extra-articular (33-A) and simple intra-articular (33-C1/C2) patterns, osteoporotic bone and obese patients (central load path, load-sharing), and where you want to minimise soft-tissue stripping. NOT for comminuted articular splits requiring formal joint reconstruction. Technique outline.

1. Reduce any simple articular split first and hold with lag screws placed OUTSIDE the nail path.
2. Flex the knee about 30-45 degrees over a bolster (relaxes gastrocnemius, opens the entry).
3. Make a medial parapatellar or transpatellar tendon portal; establish the entry point in the intercondylar notch just anterior to the PCL origin, in line with the canal on AP and lateral.
4. Ream and pass the nail; lock distally first to control the short distal segment, then proximally — confirm length, alignment and rotation before final locking.
5. Beware entry-point malposition — too anterior causes recurvatum; off-centre causes coronal malalignment.

Rehabilitation | Phase | Timing | Weight-bearing and motion | Therapy focus | |-------|--------|---------------------------|---------------| | Early | 0-6 weeks | Begin EARLY active and active-assisted knee ROM; traditionally NON or TOUCH weight-bearing for comminuted/intra-articular patterns, with a trend to earlier protected loading where fixation is robust | Prevent arthrofibrosis; wound check at 48 hours and 2 weeks | | Intermediate | 6-12 weeks | Progress weight-bearing guided by bridging callus on AP/lateral | Quadriceps and hamstring strengthening; regain full flexion/extension | | Late | Beyond 12 weeks | Advance to full weight-bearing once united | Functional and proprioceptive rehabilitation; return to activity per union | There is no single weight-bearing rule: the decision balances fracture pattern (comminuted intra-articular is more cautious), implant (a load-sharing nail tolerates earlier loading than a bridged lateral plate over comminution), bone quality, and patient factors. In frail elderly patients prolonged non-weight-bearing is poorly tolerated and itself harmful — favour constructs (nail, dual plate, nail-plate) that permit earlier weight-bearing. Special considerations. For osteoporotic or very distal fractures, use fixed-angle distal locking, longer constructs, consider augmentation (cement around screws), a retrograde nail or a NAIL-PLATE combination for added stability, and lower the threshold for distal femoral replacement in a non-reconstructable joint in a low-demand patient. The nonunion-prone construct is a SHORT, STIFF, all-locked lateral plate spanning an unsupported MEDIAL gap — counter it with a longer plate, a longer bridging working length, mixed (locked plus non-locked) screws, restored medial contact, and dual plating when the medial column is comminuted. Complications

Guidelines, registries and global practice. Implant choice (lateral locking plate, retrograde nail, dual plating, nail-plate) is converging internationally toward pattern- and patient-specific selection rather than a single default. Weight-bearing practice is shifting toward earlier protected weight-bearing in older patients to reduce the morbidity of prolonged immobilisation, where the construct permits. Distal femoral replacement is increasingly used worldwide for non-reconstructable fractures in elderly low-demand patients to enable immediate mobilisation.

AO/OTA 33 classification. The distal femur is segment 33 in the AO/OTA system. The three types define the relationship of the fracture to the articular surface and drive the entire fixation strategy.

Why the nonunion problem. The joint demands ABSOLUTE stability and the metaphysis demands RELATIVE stability, and the distal femur punishes you for confusing the two. A lateral locking plate is a fixed-angle device; when it is too stiff (a short plate, a short bridging working length, all-locked screws) it eliminates the interfragmentary micromotion that drives secondary (callus) healing, and a persistent medial gap leaves the medial column unsupported. The combination — an over-rigid lateral construct with a medial gap, compounded by high-energy comminution, periosteal stripping, open injury, diabetes, smoking or infection — is the classic setup for the medial supracondylar nonunion (an incidence up to 0-20%, higher in these risk groups). This consistent message, that construct flexibility and medial-column support matter as much as biology, underpins the modern preference for longer bridging plates, mixed screw types, far cortical locking, and dual plating of the comminuted medial column.

1. Meinberg EG, Agel J, Roberts CS, Karam MD, Kellam JF (2018). Fracture and Dislocation Classification Compendium - 2018. J Orthop Trauma. PMID 29256945. — The current AO/OTA classification, including distal femur segment 33 (A/B/C). 2. Rodriguez EK, Boulton C, Weaver MJ, et al. (2014). Predictive factors of distal femoral fracture nonunion after lateral locked plating. Injury. PMID 24314878. — Identifies mechanical (construct stiffness, medial gap) and biological risk factors for supracondylar nonunion. 3. Henderson CE, Lujan TJ, Kuhl LL, Bottlang M, Fitzpatrick DC, Marsh JL (2011). Healing complications are common after locked plating for distal femur fractures. Clin Orthop Relat Res. PMID 21161741. — Demonstrates the high rate of healing complications and the role of construct flexibility in callus formation. 4. Bottlang M, Lesser M, Koerber J, et al. (2010). Far cortical locking can improve healing of fractures stabilized with locking plates. J Bone Joint Surg Am. PMID 20660232. — Biomechanical and clinical basis for reducing construct stiffness to promote callus in metaphyseal plating. 5. Kolmert L, Wulff K (1982). Epidemiology and treatment of distal femoral fractures in adults. Acta Orthop Scand. PMID 7102269. — Classic epidemiological and treatment reference for distal femur fractures.