FCP2-401

FCP2-401

A 72-year-old man presents with chronic back and right hip pain which has been increasingly affecting him over the past few months. He finds it very difficult to mobilise in the mornings.

Clinical examination is unremarkable, apart from a limitation of right hip flexion due to pain.
Investigations show:
Haemoglobin:        12.1 g/dl (13.5-17.7)
White cell count:    8.2 x 109/l (4-11)
Platelets:                  200 x 109/l (150-400)
C reactive protein: 9 nmol/l (<10)
ESR:                         15 mm/hr (<20)
Sodium:                   140 mmol/l (135-146)
Potassium:              3.9 mmol/l (3.5-5)
Creatinine:              92 µmol/l (79-118)
ALT:                         12 U/l (5-40)
Alkaline phos:        724 U/l (39-117)
Calcium:                  2.55 mmol/l (2.20-2.67)

Which of the following is the most likely diagnosis?