Metabolic Bone Disease By Dr Prassan Tripathi

medical education

1. Metabolic Bone Disease Dr Prassan Tripathi MS ORTHO Asst Prof

2. Four Groups 1. Inadequate Osteoid synthesis - Osteopenia 2.Inadequate Mineralisation of Osteoid Osteomalacia & Rickets – a. Dietary b. Disuse 3.Decreased Osteoid synthesis and increased Osteolysis Osteoporosis – a.Senile b.Post Menopausal 4.Increase in Bone Mass – Osteosclerosis a.Paget”s disease, b.Osteopetrosis Characterized by abnormalities in calcium metabolism and/or bone cell physiology . Metabolic Bone Disease

3. Introduction Metabolic bone disease (MBD) • Encompasses a diverse group of disorders associated with altered calcium and phosphorus homeostasis. • To orthopedic surgeons; MBD is often silent until the patient presents with fracture.

4. OSTEOPOROSIS Most common metabolic bone disease. One of the most prevalent conditions associated with aging. Definition : Systemic skeletal disease characterized by low bone mass and micro architectural deterioration of bone tissue , with a consequent increase in bone fragility and susceptibility to bone fracture.

5. " Microarchitectural deterioration" refers to the thinning of the trabeculae and the loss of intertrabecular connections in bone

6. RISK FACTORS Major risk factors Age > 65 years Systemic glucocorticoid therapy of >3 months duration Mal-absorption syndrome Primary hyper parathyroidism Propensity to fall Osteopenia apparent on X-ray film Hypo- gonadism Early menopause (before age 45) Family history of osteoporotic fracture (especially maternal hip fracture) Minor risk factors Rheumatoid arthritis Past history of clinical hyperthyroidism Chronic anticonvulsant therapy Low dietary calcium intake Smoker Excessive alcohol intake Excessive caffeine intake Weight <57 kg Weight loss >10% of weight at age 25 Chronic heparin therapy

7. Clinical definition: requires the presence of a nontraumatic fracture. Histologic definition: requires normally mineralized bone to be present in reduced quantity.

8. Diagnosis Osteoporosis Bone densitometry ; gold standard 1. Detection osteoporosis before fractures. 2. Determination disease severity. 3. Estimation risk of fracture. Serial BMD measurements enabl determination of rate of bone loss or gain and thereby help in monitoring therapy. Plain film ; loss of 30% to 50% of bone is required before it is detected on conventional radiographs.

9. Ostoporosis Classification Ostoporosis Classification • Primary osteoporosis. (idiopathic) : more common – Type 1 (postmenopausal) – Type 2 (age-related or senile) • Secondary osteoporosis. – Metabolic (acromegaly, hypercorticism , hyperthyroidism, hyperparathyroidism, hypogonadism , pregnancy, diabetes mellitus) – Congenital ( osteogenesis imperfecta , Ehlers- Danlos syndrome, homocystinuria , mastocytosis , ochronosis , Gaucher's disease) – Nutritional (alcoholism, malnutrition, calcium deficiency, scurvy) – Drug-related (steroids, heparin).

10. PROXIMAL PORTION OF THE FEMUR: Analysis of the trabecular pattern of the upper end of the femur has been used as an index of osteoporosis. In this region, five anatomic groups of trabeculae can be identified. 1. Principal compressive group. 2. Secondary compressive group. 3. Greater trochanter group. 4. Principal tensile group. 5 .Secondary tensile group. Patterns of trabecular loss may correlate with increasing severity of osteoporosis. This trabecular analysis is termed as SINGH INDEX.

11. ANATOMIC GROUPS OF TRABECULA Principle compressive group Principal tensile group Secondary compressive group Secondary tensile group Greater trochanter group Wards triangle

12. NORMAL TRABECULAR PATTERNS. Proximal Femur. A. Three major patterns exist: principal compressive group (1), secondary compressive group (2), and principal tensile group (3). The confluence of these trabeculae leaves an area relatively void of structure, Ward’s triangle ( W ). B. Specimen Radiograph- the arrangement of the trabecular bundles can be discerned, defining Ward’s triangle, which is relatively devoid of bony struts. C. Specimen Radiograph. The corresponding plain film confirms the trabecular orientation and arrangement within the proximal femur and Ward’s triangle.

13. Radiological finding (1) The m/c radiologic finding is generalized osteopenia. – Cortical thinning and accentuation of Weight bearing trabeculae . – The bone surfaces are well defined, with sharp margins.

14. Radiological finding (2) Fractures - vertebral deformities, which are also common, include biconcave end plates (fish vertebrae) and anterior wedging.

15. Lateral radiograph of the lumbar spine in a 55-year-old woman with postmenopausal osteoporosis shows generalized osteopenia, compression fractures, and biconcave vertebral endplates ("fish vertebra"). Notice thin, well-defined vertebral cortices ( arrows ).

16. Radiological finding (3) Patients with osteoporosis secondary to excess steroids. – Generalized osteopenia. – Fractures with exuberant callus – Steroid-related complications; Intravertebral vacuum (nitrogen gas); Avascular necrosis. Osteomyelitis.

17. Differential considerations for diffuse osteopenia 1. Osteomalacia . – indistinct trabeculae and poorly defined interfaces between cortical and trabecular bone. – Presence of Looser's zones. 2. Hyperparathyroidism. – bone resorption at characteristic sites. 3. Multiple myeloma. – MR imaging may show areas of marrow replacement.

18. Regional or localized osteoporosis 1. Immobilization and disuse 2. Reflex sympathetic dystrophy syndrome (RSDS) 3. Transient regional osteoporosis – Transient osteoporosis of the hip. – Regional migratory osteoporosis. 4. Inflammatory arthritis. 5. Tumors 6. Infection.

19. Radiologic findings in regional osteoporosis (1) RSDS : mediated by the sympathetic nervous system and is characterized by – aggressive osteoporosis, – soft tissue swelling. The cause is usually traumatic, but the disease may also be idiopathic.

20. AP radiograph of the hand in a patient with reflex sympathetic dystrophy syndrome shows soft-tissue swelling and periarticular osteopenia.

21. RICKETS AND OSTEOMALACIA Rickets and osteomalacia Rickets and osteomalacia are similar histologically. Abnormality in vitamin D metabolism. Incomplete mineralization of normal osteoid tissue. Rickets Occurs in children Affects immature bone Osteomalacia Occurs in adult Affects mature bone

22. Pathology Rickets is associated with the inability to calcify the intercellular matrix in the growth plate, causing chondrocytes to pile up irregularly, increase in the width of the growth plate, poor mineralization of the zone of calcification and sparse bone formation in the zone of ossification. The new trabeculae are thin and weak, and the metaphysis becomes broad and cup shaped. Osteomalacia is characterized by widened osteoid seams and thinner cortices.

23. Maintain calcium and phosphate homeostasis.

24. Clinical findings of Rickets and Osteomalacia Depend in part on the aetiology and severity of the disorder, as well as the age of the patient at presentation Rickets: stunted skeletal growth. Apathetic, Irritable, Hypokinetic. Frontal bossing, softening of the skull, dental caries, rachitic rosary, kyphosis, joint enlargement, or bowing of long bones. Fractures and slipped capital femoral epiphyses.

25. Osteomalacia : Insidious course. Non specific Symptoms such as f atigue , malaise, or widespread bone pain. Proximal muscle weakness and abnormal gait (Waddling) may be present.

26. Radiologic findings of Osteomalacia The M/C radiologic sign is generalized osteopenia. Coarsened and indistinct bony trabeculae . Poorly defined interfaces between cortical and trabecular bone. Looser's zone, or pseudofracture . (more specific but less common) End plate deformities and fractures of vertebral bodies, bowing and fractures of long bones, and basilar invagination of skull. Vertebral fractures may show either a characterstic biconcave appearance or wedge shaped deformities indistinguishable from osteoporotic fractures.

27. Looser's zone. a thin transverse band of rarefaction in an otherwise normal looking bone that occur in a bilateral and symmetric distribution. These zones are due to incomplete stress fractures which heal with callus lacking in calcium. Characteristic sites; medial proximal femur, inner margins of femoral neck, proximal ulna, axillary margin of the scapula, pubic rami, and ribs. DDx ; Paget's disease or fibrous dysplasia.

28. AP radiograph of the hip in a 50-year-old man with osteomalacia shows coarsened trabecular pattern with indistinct trabeculae .

29. AP radiograph of the hip in a patient with osteomalacia shows multiple Looser zones ( arrows) in the superior pubic ramus.

30. Osteomalacia . AP radiograph of the pelvis showing osteopenia with bilateral femoral neck pseudofractures (arrows).

31. Radiologic findings of Rickets The M/C radiologic sign is generalized osteopenia. In active rickets there is thickening and widening of growth plate, cupping of the metaphysis and, and sometimes, bowing of the diaphysis. The metaphysis may remain abnormally wide even after healing has occurred. Increased lucency , widening, elongation, irregularity, and cupping of the metaphysis. – Earliest; Slight axial widening of the physis – Next; Increased lucency of the zone of provisional calcification. – More advance; The physis widens and its contour becomes irregular. Occasionally, in patients with rickets caused by chronic renal disease, increased sclerosis may be seen.

32. The regions of highest yield on radiologic evaluation of rickets are those that are undergoing rapid growth and remodelling. – Costochondral junctions of middle ribs (rachitic rosary) Radial aspects of the proximal and middle phalanges of the middle and index fingers Medial borders of - Proximal humerus . - Femoral neck - Distal femur - Proximal Tibia

33. The complication of rickets. – Skeletal deformities. – In neonates; posterior flattening and squaring of the skull, or craniotabes , may be seen. – In early childhood; bowing deformities of arms and legs are common. – Older children: scoliosis, vertebral end plate deformities, basilar invagination of the skull may be seen. Advance disease: Slipped capital femoral epiphysis.

34. A, AP radiograph of the knee in a 2-year-old girl with rickets shows generalized osteopenia and widening of the metaphysis of the proximal tibia and fibula. B, AP radiograph of the wrist in another child with rickets shows generalized osteopenia, as well as widening and irregularity of the metaphysis of the distal radius and ulna.

35. Rickets in a young child with growth plate widening and irregularity in the wrist (A) and knees (B). Note the small epiphyses in the knees.

36. Rachitic rosary. (A) and lateral (B) radiographs of the chest showing prominence of the costochondral junctions (arrows).

37. Vitamin D-resistant rickets in a 1-year-old child. (A) AP radiograph of the knees showing irregularity and widening of the growth plates. The epiphyses are small and irregular as well. (B) Three years after high-dose vitamin D therapy, the knees appear normal. There is residual femoral bowing.

38. HYPERPARATHYROIDISM Primary – Parathyroid adenoma(80%) Secondary – chronic renal insufficiency. Hyperparathyroidism may result in either diffuse bone resorption or bone formation, bone resorption usually dominates.

39. Radiologic findings of HYPERPARATHYROIDISM The M/C radiologic abnormality is generalized osteopenia. Bone resorption , bone sclerosis, brown tumors , chondrocalcinosis , soft tissue calcification, and vascular calcification. Brown tumors appear as well-defined lytic lesions. – After resection of parathyroid adenomas, the lesions may become sclerotic and may mimic blastic metastasis. Bone resorption , the most characteristic finding, is usually classified as – subchondral , trabecular, endosteal , intracortical , subperiosteal , subligamentous , and subtendinous .

40. Radiologic findings of HYPERPARATHYROIDISM Subperiosteal resorption - M/C – Usually occurs in the hands and feet. – M/C affected site: radial aspects of the middle phalanges. – Acro-osteolysis or phalangeal tufts resoption may also be present. • Trabecular resorption – Often seen in the diploic space of the skull, where it has a characteristic salt and pepper appearance. The skull displays a diffuse osteoporosis described as “ pinhead stippling” • Subchondral resorption – May be seen in the sacroiliac joints, sternoclavicular joints, acromioclavicular joints, symphysis pubis, and discovertebral junction . Vertebrae are porotic and deeply indented by ballooned discs.Collapse of the bodies is frequent

41. AP radiograph of the hand in a 66-year-old woman with primary hyperparathyroidism owing to parathyroid adenoma shows subperiosteal bone resorption ( arrows) along the radial aspect of 2nd, 3rd, and 4th middle phalanges.

42. AP radiograph of the knee in a child with hyperparathyroidism shows subperiosteal bone resorption ( arrow ) along the proximal medial tibia.

43. Lateral radiograph of the skull in a 23-year-old man with secondary hyperparathyroidism shows trabecular resorption of the diploic space ("salt and pepper" appearance).

44. Dental radiograph in another child with hyperparathyroidism shows resorption ( arrow ) of the lamina dura of the mandible.

45. Radiologic findings of HYPERPARATHYROIDISM Primary Chondrocalcinosis usually seen in the menisci of the knee, the Triangular fibrocartilage of the wrist, and the pubic symphysis Secondary Bony sclerosis; focal or generalized. Rugger-jersey appearance of spine. Soft tissue and vascular calcification.

46. AP radiograph of the wrist in an 83-year-old woman with primary hyperparathyroidism shows chondrocalcinosis ( arrow) of the triangular fibrocartilage.

47. Secondary HPT. Radiograph of the pelvis an d hips showing diffuse osteosclerosis .

48. A, AP radiograph of the spine in a patient with secondary hyperparathyroidism shows generalized bone sclerosis, small kidneys, and left renal calculi. B, Lateral radiograph of the lumbar spine in another patient with secondary hyperparathyroidism shows horizontal, bandlike ("rugger jersey") sclerosis of the vertebral bodies ( arrows ).

49. AP radiograph of the hand in a 50-year-old man with renal osteodystrophy shows acro-osteolysis ( short arrows ), subperiosteal bone resorption ( long arrows ), and vascular calcifications.

50. Secondary HPT. Radiograph of the hand showing resorption of the first to third tufts with soft tissue calcification (1). There is articular calcification (2), and subperiosteal and subligamentous resorption (3).

51. Laboratory Findings Hypercalcemia Hypophosphatemia High Alkaline Phosphatase Hypercalciuria Hyperphosphaturia .

52. The differential diagnosis of HYPERPARATHYROIDISM Focal subperiosteal resorption involving a single bone – Neoplasms or osteomyelitis. • Bone sclerosis in patients with secondary hyperparathyroidism. – Metastatic disease, radiation-induced bone disease, hypoparathyroidism , myelofibrosis , mastocytosis , sickle-cell disease, and Paget's disease. • Chondrocalcinosis – Pyrophosphate arthropathy (CPPD) or hemochromatosis. • Brown tumors – includes other focal lytic lesions, such as giant cell tumor and fibrous dysplasia.

53. HYPOPARATHYROIDISM The M/C cause is excision of or trauma to the parathyroid glands during thyroidectomy. – may not be recognized for years after surgery. Characterized by low serum calcium and high serum phosphorus levels.

54. Clinical presentation: Neuromuscular dysfunction – twitching, carpopedal spasm and laryngeal spasms, positive Chvostek’s and Trousseau signs and convulsions. Short stature. Delay or failure of tooth eruption. Gastrointestinal complaints.

55. Radiologic findings of HYPOPARATHYROIDISM Radiologic findings are varied. Bony sclerosis. = M/C finding Focal or generalized Subcutaneous calcification. Calvarial thickening Basal ganglia calcification Hypoplastic dentition Premature physeal fusion Spinal ossification. Occasionally : Osteoporosis, Enthesopathy , Dense metaphyseal bands.

56. Lateral radiograph of the skull in a 5-year-old girl with pseudohypoparathyroidism shows thickening ( arrows) of the calvarium .

57. differential diagnosis of HYPOPARATHYROIDISM Widespread bony sclerosis. – Blastic metastasis, myelofibrosis , renal osteodystrophy , sickle-cell disease, and fluorosis. • Dense metaphyseal bands. – Leukemia therapy, heavy-metal poisoning, or hypothyroidism. • Calcifications of the basal ganglia – Toxoplasmosis or cytomegalovirus infections, after radiation therapy, and after carbon monoxide exposure. • Subcutaneous calcifications. – Collagen-vascular diseases, hypervitaminosis D, and renal osteodystrophy .

58. Pseudohypoparathyroidism Rare Inherited disorder first described by Albright that is caused by congenital lack of adenyl cyclase . End-organ resistance to parathyroid hormone. X-linked dominant trait More common in women. Shares many features with hypoparathyroidism .

59. Radiologic findings of Pseudohypoparathyroidism Similar to those of hypoparathyroidism Bony sclerosis, Soft tissue calcification, Dense metaphyseal bands, Calvarial thickening and Basal ganglia calcification. In addition Short metacarpals, metatarsals, and phalanges; diaphyseal exostoses ; and cone-shaped epiphyses. Typically, the first, fourth, and fifth rays are shortened. Growth deformities Bowing of long bones.

60. Ps eudohypoparathyroidism . (A,B) AP radiographs of the h ands showing shortening of the fourth and fifth metacarpals.

61. AP radiograph of the hand in another child with pseudohypoparathyroidism shows short 3 rd , 4 th , and 5 th metacarpals.

62. Pseudopseudohypoparathyroidism Incomplete genetic manifestation of PHP. End-organ resistance to parathyroid hormone. Share most of their clinical and radiologic features of pseudohypoparathyroidism .

63. RENAL OSTEODYSTROPHY Bone disease in patients with chronic renal insufficiency. It combines features of rickets, osteomalacia , secondary hyperparathyroidism, and osteoporosis. Aluminum toxicity is an additional component that may be seen in patients undergoing dialysis. In children with chronic renal failure, the findings of rickets dominate, whereas in adults the findings of secondary hyperparathyroidism are more prominent.

64. Radiologic findings in RENAL OSTEODYSTROPHY Combination of the findings of rickets, osteomalacia , secondary hyperparathyroidism, and osteoporosis Periosteal neostosis ( lucency between the periosteum and subjacent bone) may be present. It is usually seen in asymmetric distribution in the metatarsals, femur, and pubic rami.

65. The differential diagnosis of RENAL OSTEODYSTROPHY Periosteal neostosis – hypertrophic osteoarthropathy , osteomyelitis, or neoplasm. Soft tissue calcification – Collagen-vascular diseases, idiopathic tumoral calcinosis , hydroxyapatite crystal deposition disease, and hypervitaminosis D.

66. The most common complications in patients with renal osteodystrophy are insufficiency fractures. In patients who have had renal transplantation, osteonecrosis, insufficiency fractures, tendinitis, and tendon ruptures are common.

67. Frog-lateral radiograph of the hip in a patient with osteonecrosis of the femoral head shows a characteristic subchondral lucency ( arrow) and collapse of the femoral head.

68. PAGET'S DISEASE A common disorder of unknown aetiology that is characterized by excessive and abnormal remodelling of bone. Men > women Age > 40 years. Polyostotic > monostotic .

69. PAGET'S DISEASE Asymptomatic. • Bone pain, progressive bony enlargement, bowing of long bones, or fractures at presentation. • Deafness – from cranial-nerve compression at the skull base or from middle-ear ossicle involvement. • The spinal cord compressed – basilar invagination of the skull or enlargement of the vertebrae.

70. Radiologic findings of PAGET'S DISEASE Epiphyseal involvement with sharply demarcated lysis that advances down the diaphysis is quite specific. Three sequential stages may be seen: 1. Lytic - most common in skull and long bones. 2. Mixed 3. Sclerotic - typically involves the axial skeleton. The hallmarks of advanced Paget's disease are bone enlargement and increased bone sclerosis. Cortical and trabecular thickening and distortion are also frequently present.

71. Radiologic findings of PAGET'S DISEASE Spine – M/C in lumbar region: picture-frame vertebra, ivory vertebra, or compression fractures. • Skull – Lytic phase, or osteoporosis circumscripta , usually begins in the frontal or occipital bones. – More advanced disease in the skull manifests a cotton wool appearance of mixed sclerosis and lysis . • Pelvis – The earliest finding = thickening of the iliopectineal line. – Occasionally, patchy areas of lucency and sclerosis. – Protrusion deformity of the acetabula is a well-recognized complication of advanced disease of the pelvis.

72. Radiologic findings of PAGET'S DISEASE Long bones – Lysis of subarticular bone is seen initially. – A wedge of lucency down the diaphysis: flame-shaped or blade-of-grass. – In the tibia, the lytic phase occasionally begins in the diaphysis. – Advanced disease of the long bones is characterized by coarsened trabecula , bony sclerosis, bony enlargement, and deformity.

73. A, Frontal radiograph of the pelvis in a patient with advanced Paget's disease shows bony enlargement, bone sclerosis, and trabecular disorganization involving the right femur, right hemipelvis , and sacrum. B, Frontal radiograph of humerus in another patient with advanced Paget's disease shows bony enlargement, cortical and trabecular thickening, and trabecular disorganization.

74. Frontal radiograph of the femur in a patient with advanced Paget's disease shows bowing deformity of the femur along with bony enlargement, bone sclerosis, cortical thickening, and trabecular disorganization.

75. Complications of PAGET'S DISEASE Basilar invagination Spinal stenosis Premature osteoarthritis Insufficiency fractures Osteomyelitis Neoplasms: osteosarcomas. Sarcomatous degeneration: common in patients with widespread disease

76. Frontal radiograph of the pelvis in a patient with widespread Paget's disease shows enlargement and cortical thickening of the pelvis. Additionally, there is an expansile lytic lesion ( arrows) in the ischium, representing malignant degeneration of Paget's disease into fibrosarcoma .