Table 2 Unadjusted associations with re-operation

Demographics

 Age < 75 y.o.

2.50 (1.45–4.35)

0.001

Medical comorbidities

 Charlson Comorbidity Score

0.88 (0.80–0.97)

0.010

 Dementia

0.22 (0.07–0.74)

0.014

Social history

 Smoking

2.58 (1.40–4.73)

0.002

Operation characteristics

 Type of nail

  Long Affixus nail

Ref.

Ref.

  Long Gamma nail

2.29 (1.33–3.97)

0.003

Radiographic measurements

 Femoral neck shaft angle^a

  Normal

Ref.

Ref.

  Coxa valga

0.27 (0.12–0.62)

0.002

  Coxa vara

3.92 (1.30–11.83)

0.015

 Number of fragments (comminution)

  Simple

1.49 (0.77–2.85)

0.234

  Moderate

Ref.

Ref.

  Severe

2.29 (1.19–4.41)

0.013

 Lateral cortex gap size (mm)

  ≥  4

Ref.

Ref.

  5–9

2.64 (1.43–4.87)

0.002

     ≥ 10

3.47 (1.62–7.41)

0.001

 Posterior cortex gap size (mm)

   ≤    4

Ref.

Ref.

  5–9

2.54 (1.34–4.83)

0.004

  ≥ 10

3.77 (1.40–10.12)

0.009

 Reduction angle grouped^b (degrees)

  Valgus 5–varus 5

Ref.

Ref.

  Valgus > 5

1.67 (0.51–5.41)

0.397

  Varus 5–10

3.25 (1.69–6.24)

 < 0.001

  Varus > 10

6.76 (2.49–18.37)

 < 0.001

Complications

 Failure at lag screw junction

2.39 (0.47–5.03)

 < 0.001

 Self-dynamisation

6.11 (2.38–15.63)

 < 0.001

 Cut-out

22.76 (2.69–192.52)

0.004

 Non-union

15.14 (8.01–28.63)

 < 0.001

 Fracture-related infection

17.85 (3.76–84.79)

 < 0.001

 Massive transfusion

7.32 (1.31–40.87)

0.023