Calcium and Vitamin D
Moderate evidence supports use of supplemental vitamin D and calcium in patients following hip fracture surgery.

Four moderate strength studies (Bischoff-Ferrari et al 150, Prince et al151, Harwood et al152, and Chapuy et al153) show benefits of either supplemental calcium, vitamin D or both to reduce fall risk and prevent fractures in the elderly.   There is a high prevalence of vitamin D deficiency among hip fracture patients (Bischoff-Ferrari et al150) and hip fracture patients have a 5-10x increased risk of a second hip fracture and other fragility fractures (Harwood et al152).  In a moderate strength double-blinded study in elderly women with hip fractures  (Bischoff-Ferrari et al), 98% of patients were found to be vitamin D deficient (<30 ng/ml) and hospital readmission rates were decreased by 39% in patients treated with daily supplementation of 2000 IU versus 800 IU vitamin D.  In a moderate strength randomized clinical trial in 3,270 elderly women, Chapuy et al153 showed that supplemental calcium and 800 IU vitamin D reduced the risk of hip fractures by 43% and non-spine fractures by 32% over 18 months.  Another moderate strength 5 year double-blind placebo-controlled study (Prince et al151) showed a reduction in fractures in the elderly population with supplemental calcium carbonate (1200mg/d), but the results were limited due to poor long term compliance.  A randomized controlled trial of hip fracture patients (Harwood et al152) showed vitamin D supplementation either orally or by injection increased bone mineral density and reduced the incidence of falls, with calcium co-supplementation having a positive effect.
Risks and Harms of Implementing this Recommendation
Calcium and vitamin D supplements are generally safe with few side effects. Some studies show that supplemental calcium in adults aged 65 or older is associated with an increased risk of constipation or nephrolithiasis. 

Future Research
Further placebo controlled randomized clinical trials controlling for non-compliance are needed to clarify benefits and risks of calcium and vitamin D supplementation in patients 65 and older, as well as to identify target levels to achieve optimal benefits as there appears to be a dose dependent relationship in outcomes.  Measurement of the serum calcium, albumin, 25-hydoxyvitamin D, and creatinine levels may reveal secondary causes of osteoporosis (e.g. hyperparathyroidism, malignancy, vitamin D  deficiency or chronic kidney disease) and could guide use of calcium, vitamin D, or nutritional supplements which may improve outcomes.