The Hip: Preservation, Replacement and Revision

Osteomalacia



- Discussion:
    - is a type of metabolic bone disease in which the essential problem is a lack of available calcium or phosphorus (or both) for mineralization of newly formed osteoid;
    - children w/ rickets & adults w/ osteomalacia present w/ similar findings;
    - etiology of rickets and osteomalacia:
          - hyperthyroid induced osteopenia:
          - chronic use of anticonvulsant medication:
          - deficiency states:
                 - vitamin-D deficiency: (strict vegetarians or an extremely low fat diet);
                 - gastrointestinal and bilary causes;
          - renal osteodystrophy
          - fibrous dysplasia or neurofibroma:
                 - osteomalacia & rickets are rare osteoendocrine or neuroendocrine manifestations of fibrous dysplastic or neurofibromatous dz;
    - anatomic changes in rickets and osteomalacia:
          - anatomical and pathological changes differ according to age of patient and the severity of the disorder;
          - rickets affects the growing skeleton & thus affects both the epiphyseal plates as well as the bones of children;
          - osseous changes in osteomalacia are similar to those in children but are much less evident because adult skeleton is metabolically less active;

- Clinical Manifestations:
    - pts generally complain of easy fatigability, malaise, and bone pain;
    - pain is diffuse and poorly localized and is accompanied by a general tenderness of bones;
    - frx in an elderly individual that is thought to be the result of osteoporosis may be first sign of osteomalacia, & these patients must be evaluated carefully;
          - all symptomatic elderly patients should be screened for occult disease;
    - bizarre complaints may give impression that patient has mental aberration;
    - muscular weakness is often seen in severe cases;
         - proximal muscle weakness may be evident & pt may have T-burg gait;


- Radiographs:
    - Looser's zones:
           - osteoid seams are insufficiency types of stress frx which are commonly seen in patients with osteomalacia;
           - they are more common in adults than in children;
    - patients may have findings of osteomalacia / renal osteodystrophy such as decreased mineralization, coarsened texture of the bones, "rugger-jersey" appearance of spine, and, occasionally, bowed long bones;
    - most of these patients have chronic renal disease;


- Histologic examination:
    - biopsy:
           - biopsy is frequently necessary to provide diagnosis, which allows assessment of the number and thickness of osteoid seams per unit area;
           - look for wide osteoid seams;
           - there is less mineralized trabecular & cortical bone per unit volume of bone;
           - tetracycline labeling helps confirm decreased mineralization of osteoid seams;
    - stress frx:
           - unmineralized areas (also called Looser's zones or pseudofractures) are occasionally seen roentgenographically;
           - these zones are caused by rapid resorption & slow mineralization, are generally perpendicular to bone cortex;
           - if stress frx occurs, it may be surrounded by a collar of callus;
    - osteoid seam:
           - osteoid seams in osteomalacia are wider than seam found in other diseases;
           - diff dx: widened osteoid seams may be found in:
                  - rickets;
                  - osteomalacia;
                  - hyperparathyroidism;
                  - fibrous dysplasia;
                  - bone-forming tumors;



- Laboratory Aspects: Osteomalacia:
    - hypocalcemia
    - hypophosphatemia:
           - phosphorus level is low or very low depending on type of osteomalacia, except in renal osteodystrophy;
           - renal osteodystrophy;
                  - phosphorus level is invariably high & calcium level will be quite low;
    - alk phos:
           - usually elevated in all forms of osteomalacia (except hypophosphatasia)



- Reference:

Massive osteolysis.



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

Last updated by Data Trace Staff on Thursday, August 23, 2012 10:50 am