
A 22 year old mechanic presents to ED complaining of a painful finger on his right hand following an injury at work 5 days ago. His GP started a course of oral antibiotics but his symptoms are not improving. On examination, the finger is held in slight flexion, tender on palpation and painful on passive extension.
| Injury | Clinical features | 
|---|---|
| Superficial flexor tendon | 
  | 
| Deep flexor tendon | 
  | 
| Complete division of extensor tendon at DIPJ | 
  | 
| Central slip division of extensor tendon at PIPJ | 
  | 
| Median nerve | 
  | 
| Ulnar nerve | 
  | 
| Radial nerve | 
  | 
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| Biochemistry | Normal Value | 
|---|---|
| Sodium | 135 – 145 mmol/l | 
| Potassium | 3.0 – 4.5 mmol/l | 
| Urea | 2.5 – 7.5 mmol/l | 
| Glucose | 3.5 – 5.0 mmol/l | 
| Creatinine | 35 – 135 μmol/l | 
| Alanine Aminotransferase (ALT) | 5 – 35 U/l | 
| Gamma-glutamyl Transferase (GGT) | < 65 U/l | 
| Alkaline Phosphatase (ALP) | 30 – 135 U/l | 
| Aspartate Aminotransferase (AST) | < 40 U/l | 
| Total Protein | 60 – 80 g/l | 
| Albumin | 35 – 50 g/l | 
| Globulin | 2.4 – 3.5 g/dl | 
| Amylase | < 70 U/l | 
| Total Bilirubin | 3 – 17 μmol/l | 
| Calcium | 2.1 – 2.5 mmol/l | 
| Chloride | 95 – 105 mmol/l | 
| Phosphate | 0.8 – 1.4 mmol/l | 
| Haematology | Normal Value | 
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl | 
| White Blood Cells | 4.0 – 11.0 x 109/l | 
| Platelets | 150 – 450 x 109/l | 
| MCV | 80 – 96 fl | 
| MCHC | 32 – 36 g/dl | 
| Neutrophils | 2.0 – 7.5 x 109/l | 
| Lymphocytes | 1.5 – 4.0 x 109/l | 
| Monocytes | 0.3 – 1.0 x 109/l | 
| Eosinophils | 0.1 – 0.5 x 109/l | 
| Basophils | < 0.2 x 109/l | 
| Reticulocytes | < 2% | 
| Haematocrit | 0.35 – 0.49 | 
| Red Cell Distribution Width | 11 – 15% | 
| Blood Gases | Normal Value | 
|---|---|
| pH | 7.35 – 7.45 | 
| pO2 | 11 – 14 kPa | 
| pCO2 | 4.5 – 6.0 kPa | 
| Base Excess | -2 – +2 mmol/l | 
| Bicarbonate | 24 – 30 mmol/l | 
| Lactate | < 2 mmol/l |