Distal Femur Fracture - Hyperexcision

Last updated: November 17, 2025

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Distal femur fractures invole the distal metaphyseal-diaphyseal junction of the femur +/- intra-articular extention to the femoral condyles. Majority of distal femur fractures are treated operatively.

Fractures of the distal femur account for 7% of femur fractures. Like most fractures it has a bimodal distribution with high-energy mechanism is common in the young population while low-energy mechanism is more common in the elderly.

AO/OTA Classification of distal femur fracture

Category	AO/OTA	AO/OTA
Bone	Femur	3
Location	Distal segment	33
Types	Extra-articular (A)	33-A
	Partial-articular (B)	33-B (33 – B3 is a Hoffa fragment)
	Complete articular (C)	33 – C

Anatomy
- Shaft of femur is aligned with anterior half of the lateral condyle
- There is a anatomic axis 9 degrees of valgus (7 – 11 degrees)
- On axial section teh distal femur is trapezoidal in shape which has implications for implant placement and the prominence of screws
Mechanism of injury
- High-energy (significantly displaced)
  - Motorvehicle accident
  - Fall from height
- Low-energy (less displacement)
  - Fall from standing height on flexed knee (in weakened bone)
Deforming forces
- Shortening is caused by the quadriceps and hamstrings
- Apex posterior angulation and posterior displacement is caused by gastrocnemius (can obstruct the popliteal vessels)
- Varus angulation caused by hip adductors
Associated injuries
- Open fracture (5 – 10%)
- Knee ligament injury (20%)
- Tibial plateau fracture
- Patella fracture
- Acetabular fracture
- Femoral neck fracture
- Femoral shaft fracture
Signs and symptoms
- Inability to bear weight
- Pain of the distal femur
  - Worse with knee movement
- Deformity of the distal thigh and knee
Physical examination
- Tenderness
- Swelling
- Ecchymosis
- Neurovascular examination (potential injury to the popliteal artery)
Investigations
- X-ray: AP and lateral views + joint above and below
  - Double density on AP (Hoffa fragment)
  - Paradoxical notch view on AP (articular fragment in recurvatum)
- CT-scan: to demonstrate intra-articular involvement, coronally oriented hoffa fragment and pre-operative planning
  - Hoffa fracture in the coronal plane
  - Separate osteochondral fragments int he area of the intervondylar notch
- Ankle-brachial index (ABI): to rule out vascular injury
- CT angiogram: Indicated if ABI is < 0.9
Hoffa fragment
- A Hoffa fragment is an intra-articular distal femoral fracture in the coronal plane
- It occurs in 38% of distal femur fractures and is easy to miss on plain radiograph (missed 31% of the time)
- Affects the lateral condyle more than the medial condyle (80%)
Treatment of distal femur fracture
- Resuscitation
- Splinting with a bohler-brown splint or thomas splint with a flexion device to minimize compression of the popliteal vessels
- External fixation
- Open reduction internal fixation (ORIF)
- Closed reduction and intramedullary fixation (IMN)
- Non-operative treatment with a long-leg cast followed by hinged knee brace (rare)
- Distal femur Arthroplasty
- Early range of motion exercises to prevent stiffness
- Non-weight bearing until evidence of fracture union
Open reduction and internal fixation
- Anterior to posterior screw for Hoffa fragment
- Dynamic condylar screw (DCS) plate
- Lateral locked distal femur plates (31% rate of non-union)
- Intramedullary nail
Indications for external fixation
- Temporary measure
  - Unstable polytrauma
  - Extensive soft tissue damage
  - Contamination requiring multiple debridement
- Definitive measure
  - Severe open and/or comminuted fracture
  - Unstable for surgery
Indications for arthroplasty
- Pre-existing osteoarthritis with amenable fracture pattern
Indications for non-operative management (rare)
- Medical contraindication to surgery
- Non-ambulatory
- Non-displaced fracture
- Impacted, stable fracture
- Non-reconstructable fracture
- Severe osteopaenia
- Lack of experienced operative treatment, instruments or facilities
Early complications of the distal femur fracture
- Injury to popliteal vessels and sciatic nerve
- Fat embolism
- Deep venous thrombosis and pulmonary embolism
Late complications of distal femur fracture
- Knee pain and/or stiffness
- Post-traumatic osteoarthritis
- Malunion
- Non-union
- Implant failure

Reference Intervals ›

Biochemistry

ACTH	P: <80 ng/L
ALT	P: 5–35 U/L
Albumin	P: 35–50 g/L
Aldosterone	P: 100–500 pmol/L
Alk. phosphatase	P: 30–130 U/L
α-Amylase	P: 0–180 IU/dL
α-Fetoprotein	S: <10 kU/L
Angiotensin II	P: 5–35 pmol/L
ADH	P: 0.9–4.6 pmol/L
AST	P: 5–35 U/L
Bicarbonate	P: 24–30 mmol/L
Bilirubin	P: 3–17 μmol/L
BNP	P: <50 ng/L
CRP	P: <10 mg/L
Calcitonin	P: <0.1 mcg/L
Calcium (ionized)	P: 1.0–1.25 mmol/L
Calcium (total)	P: 2.12–2.60 mmol/L
Chloride	P: 95–105 mmol/L
Cholesterol	P: <5.0 mmol/L
VLDL	P: 0.128–0.645 mmol/L
LDL	P: <2.0 mmol/L
HDL	P: 0.9–1.93 mmol/L
Cortisol AM	P: 450–700 nmol/L
Cortisol Midnight	P: 80–280 nmol/L
CK ♂	P: 25–195 U/L
CK ♀	P: 25–170 U/L
Creatinine	P: 70–100 μmol/L
Ferritin	P: 12–200 mcg/L
Folate	S: 2.1 mcg/L
FSH	P: 2–8 U/L ♂; >25 menopause
GGT ♂	P: 11–51 U/L
GGT ♀	P: 7–33 U/L
Glucose (fasting)	P: 3.5–5.5 mmol/L
Growth hormone	P: <20 mu/L
HbA1C (DCCT)	B: 4–6%
HbA1C (IFCC)	B: 20–42 mmol/mol
Iron ♂	S: 14–31 μmol/L
Iron ♀	S: 11–30 μmol/L
Lactate (venous)	P: 0.6–2.4 mmol/L
Lactate (arterial)	P: 0.6–1.8 mmol/L
LDH	P: 70–250 U/L
LH	P: 3–16 U/L
Magnesium	P: 0.75–1.05 mmol/L
Osmolality	P: 278–305 mosmol/kg
PTH	P: 0.8–8.5 pmol/L
Potassium	P: 3.5–5.3 mmol/L
Prolactin ♂	P: <450 U/L
Prolactin ♀	P: <600 U/L
PSA	P: 0–4 mcg/mL
Protein (total)	P: 60–80 g/L
Red cell folate	B: 0.36–1.44 μmol/L
Renin (erect)	P: 2.8–4.5 pmol/mL/h
Renin (recumbent)	P: 1.1–2.7 pmol/mL/h
Sodium	P: 135–145 mmol/L
TBG	P: 7–17 mg/L
TSH	P: 0.5–4.2 mU/L
T4	P: 70–140 nmol/L
Free T4	P: 9–22 pmol/L
TIBC	S: 54–75 μmol/L
Triglycerides	P: 0.50–2.3 mmol/L
T3	P: 1.2–3.0 nmol/L
Troponin T	P: <0.1 mcg/L
Urate ♂	P: 210–480 μmol/L
Urate ♀	P: 150–390 μmol/L
Urea	P: 2.5–6.7 mmol/L
Vitamin B12	S: 0.13–0.68 nmol/L
Vitamin D	S: 50 nmol/L

Arterial Blood Gases

pH	7.35–7.45
PaCO₂	4.7–6.0 kPa
PaO₂	>10.6 kPa
Base excess	±2 mmol/L

Urine

Cortisol (free)	<280 nmol/24h
Hydroxyindole acetic acid	16–73 μmol/24h
Hydroxymethylmandelic acid	16–48 μmol/24h
Metanephrines	0.03–0.69 μmol/mmol cr.
Osmolality	350–1000 mosmol/kg
17-Oxogenic steroids ♂	28–30 μmol/24h
17-Oxogenic steroids ♀	21–66 μmol/24h
17-Oxosteroids ♂	17–76 μmol/24h
17-Oxosteroids ♀	14–59 μmol/24h
Phosphate (inorganic)	15–50 mmol/24h
Potassium	14–120 mmol/24h
Protein	<150 mg/24h
Protein/creatinine ratio	<3 mg/mmol
Sodium	100–250 mmol/24h

Haematology

WCC	4.0–11.0 ×10⁹/L
RBC ♂	4.5–6.5 ×10¹²/L
RBC ♀	3.9–5.6 ×10¹²/L
Hb ♂	130–180 g/L
Hb ♀	115–160 g/L
PCV ♂	0.4–0.54 L/L
PCV ♀	0.37–0.47 L/L
MCV	76–96 fL
MCH	27–32 pg
MCHC	300–360 g/L
RDW	11.6–14.6%
Neutrophils	2.0–7.5 ×10⁹/L (40–75%)
Lymphocytes	1.0–4.5 ×10⁹/L (20–45%)
Eosinophils	0.04–0.44 ×10⁹/L (1–6%)
Basophils	0–0.10 ×10⁹/L (0–1%)
Monocytes	0.2–0.8 ×10⁹/L (2–10%)
Platelets	150–400 ×10⁹/L
Reticulocytes	0.8–2.0% / 25–100 ×10⁹/L
Prothrombin time	10–14 s
APTT	35–45 s

Paediatric

Pulse Rate (bpm)
Neonate	140–160
Infant <1yr	120–140
1–5 years	110–130
5–12 years	80–120
>12 years	70–100
Respiratory Rate (tachypnoea)
0–2 months	≥60/min
2–12 months	≥50/min
1–5 years	≥40/min
>5 years	≥30/min
Blood Pressure (mmHg)
Term	65/45
1 year	75/50
4 years	85/60
8 years	95/65
10 years	100/70
Weight Formulas
3–12 months	(a + 9)/2 kg
1–6 years	2a + 8 kg
>6 years	(7a − 5)/2 kg
Haemoglobin (g/dL)
Term newborn	13–20
1 month	11–18
2 months	10–15
1–2 years	10–13
>2 years	11–14
MUAC (6 months–5 years)
Obese	>17.5 cm
Normal	13.5–17.4 cm
At risk	12.5–13.4 cm
Moderate malnutrition	11.5–12.4 cm
Severe malnutrition	<11.5 cm
Developmental Milestones
Social smile	1.5 months
Head control	4 months
Sits unsupported	7 months
Crawls	10 months
Stands unsupported	10–12 months
Walks	12–13 months
Talks	18 months
CSF WBC (/mm³)
Term newborn	0–25
>2 weeks	0–5

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