A 36-year-old woman presented with her 2-year child in the out-patient orthopaedic department of our hospital. She complained that her little boy was unable to walk properly without support. The child looked intelligent, aware of what was happening around him. However he was hypotonic with muscular weakness, cranial sutures were still widened and dental eruption was delayed. No other abnormal findings were found at the physical examination. Urine and essential blood tests were normal except for an increase in the serum alkaline phosphatase (1,253 IU/ml). The X-ray performed to his legs showed radiologic alteration at the epiphyseal growth plate due to decreased calcification of the hypertrophic zone and inadequate mineralization of the primary spongiosa. The orthopaedist asked to visit also the 15-year-old sister who was accompanying the little infant. The young woman had skeletal pain and most significantly a ''rachitic rosary'' due the prominence of the costochondral junctions.These findings confirmed the suspect of the orthopaedist and he diagnosed in both patients the presents of rickets.While speaking with the mother he found out that she wanted her children to be as much white as possible and did not let them get in contact with sunlight and obliged her daughter to dress the dark nighab since an early age. The physician advised the mother to give her children food rich with calcium and oral vitamin D, but explained and convinced her that sunlight is more important for the good health of her children than any other treatment. At the 6 months follow up, the little boy was fine and able to walk correctly and the clinical findings for his sister were improving.

Background Hypophosphatemic rickets is associated with delayed walking, bone deformities, growth failure and physical dysfunction that can limit daily activities. Treatment consists of phosphate salts and calcitriol. We report a case that received denosumab with marked improvement in her condition. Case presentation A 24-year-old Yemeni female with hypophosphatemic rickets presented to an endocrinologist with severe weakness and severe pain in the extremities, she had been bedridden for the last 4 years. Bone density showed severe osteoporosis (T score of hip was − 5.0 and Z score of hip was − 5.0, T score of the spine was − 6.0 and Z score of the spine was − 6.1) so the patient was started on denosumab in addition to calcitriol and after 7months she was feeling stronger and felt she could stand assisted and was walking with assistance within 9 months and after 1.5 years of treatment she was walking unassisted. Conclusion Denosumab is an effective treatment for osteoporosis, we used it in our patient in addition to calcitriol because she had severe osteoporosis due to long standing hypophosphatemic rickets that had not been treated properly, the patient improved markedly and regained the ability to walk again after being bedridden for 4 years. It may be a drug to consider in such cases although further studies need to be done to confirm this.