The Hip: Preservation, Replacement and Revision

Renal Osteodystrophy

- See:
         - Calcitriol
         - Hyperparathyroidism
         - Renal Failure: (Orders for the CRF Patient)
         - Renal Spondyloarthropathy
         - Vit D

- Effects on Adult Bone:
    - abnormalities of renal function can produce profound bone disease;
    - bone disease seen in renal failure is called renal osteodystrophy;
    - early stages of osteodystrophy:
          - effects on bone are primarily due to action of parathyroid hormone on osteocyte-osteoblast lining cell system, which is probably result of decreased phosphate excretion by the kidney;
          - w/ decreased phosphate excretion, there is elevation of plasma phosphate & complexing of calcium & phosphate in bone fluid;
          - as result, increasing amounts of PTH hormone are required to move the same amount of calcium from bone in order to maintain the plasma calcium at a constant level;
          - due to elevated parathyroid hormone levels, there is increase in number of bone remodeling centers & increase in bone turnover;
    - late stages:
          - when the glomerular filtration falls below 25% of normal, increased secretion of PTH is no longer able to maintain normal phospate levels, and the serum phosphate increases;
          - mineralization of previously osteomalacic bone then occurs, and osteosclerosis develops; (see ossification of soft tissue);
    - end stages:
          - diminished ability of kidney to hydroxylate vit D leads to a decrease in circulating levels of 1,25(OH)2D3 & produces decrease in intestinal calcium absorption;
          - calcification of osteoid is inhibited owing to deficiency of 1,25(OH)2D3, and owing to metabolic acidosis and other circulating inhibitors of mineralization that occur in uremic state;
    - net effect of renal dz on bone:
          - is combination of secondary hyperparathyroidism, osteomalacia, and osteosclerosis;
          - when bone disease becomes severe, pathologic fractures may occur, esp in ribs, pelvis, and hips;
          - uremic pts w/ advanced hyperparathyroidism appear prone to nontraumatic aseptic necrosis of the hips;
          - bone pain, frx, and concomitant muscle disease may be the major impediment to rehabilitation in chronic uremia;

- Effects in Children:
    - bone may appear diffusely sclerotic;
    - varus deformity of the proximal femurs may occur as a result of bone softening and osteomalacia;
    - growth plates are widened and zone of provisional calcification is poorly defined



Original Text by Clifford R. Wheeless, III, MD.

Last updated by Data Trace Staff on Monday, August 13, 2012 11:03 am