Hip Fracture Surgery and Oral Nutritional Supplements (HIATUS)

Inclusion Criteria:

• Age (70+);
• Had an acute hip fracture and surgical treatment
• Able to walk at least 3 meters without assistance of another person, with or without a walking aid other than a wheeled walker prior to hip fracture MMSE >=18 (proxy will be informed in addition if MMS-score ≤ 24)
• Able to perform the SPPB at baseline
• No prior hip fracture
• Patient (and/or his/her legal representatives/relatives) understands the study procedure, alternative treatments available and risks involved with the study, and voluntarily agrees to participate by giving his/her (or his/her legal representative's/relatives) written informed consent.

Exclusion Criteria:

• Baseline visit can not be performed between the second and tenth postoperative day.
• Milk protein allergy
• Patients with conservative treatment for hip fracture
• Serum calcium adjusted for albumin of > 2.6 mmol/L
• Pathologic fracture in the last year (except for fractures due to osteoporosis)
• Chemo therapy / Radiation /antihormonal therapy due to cancer in the last year
• Treatment which has an effect on calcium metabolism (e.g. PTH, calcitonin, chronic cortisone intake > 5mg/day in the last 12 months (except for inhalation and sporadic infiltration))
• Oral vitamin D intake of more than 1000 IU per day during the last 3 months before the study
• Unwilling to stop multi-vitamin, calcium supplementation, and vitamin D supplementation during the trial (maximal calcium supplement intake 250mg/d; no additional vitamin D supplementation). We will inform the treating physician that we initiated vitamin D supplementation as standard of care.
• Severe visual or hearing impairment
• Unwilling or unable to take study medication
• Diseases with a risk of recurrent falling (e.g. Parkinson's disease/syndrome, Hemiplegia after stroke, symptomatic stenosis of the spinal canal, polyneuropathy, epilepsy, recurring vertigo, recurring syncope) BMI ≥ 40
• Estimated creatinine clearance < 15 ml/min (estimated Creatinine Clearance cockcroft and Gault)
• Malabsorption syndrome (celiac diseases, inflammatory bowel disease, hepatic and/or pancreas dysfunction)
• Diseases that may enhance serum calcium: sarcoidosis, lymphoma, primary hyperparathyroidism
• Kidney stone in the last 10 years
• Patient heavily consumes alcohol containing products defined as greater than (>) 3 drinks (beer, wine, or distilled spirits) of alcoholic beverages per day.
• Patients who are planning a stay in a "sunny" location (e.g. winter sun resort) for more than one month during the trial
• Medication which has an effect on serum 25-hydroxyvitamin D level (e.g. certain anticonvulsants (e.g. Phenobarbital, Carbamazepin, Phenytoin) M. Paget (Ostitis deformans)
• Inflammatory arthritis (e.g. rheumatoid arthritis, reiter syndrome, psoriasis arthritis)
• Uncontrolled metabolic conditions, or psychiatric conditions that might make tolerance or evaluation of the feeding formula difficult
• Severe acute and/or chronic disease that makes the performance of the study assessments impossible (e.g. severe infection/sepsis, myocardial infarction, heart failure, respiratory failure or renal failure);
• Patient is taking peripherally acting anti-adiposity drugs (e.g. Xenical®, formoline L112®, (Acomplia®))
• Patients taking protein supplements (>15g per serving more than once a week) or are unwilling to stop any protein supplements during the trial Participation in a study in the last 6 month, except for studies without drug-application, or any influence of the study-medication can be excluded
• Patient is unlikely to adhere to the study procedures, to keep appointments, or is planning to relocate during the study.