Orthopaedics
Trauma and orthopaedics for the Indian MBBS final-year exam — fractures, dislocations, bone and joint infection, tumours, the spine, arthritis, paediatric and regional orthopaedics. Full-length explanation-first answers with diagrams.
Definition
Osteoporosis is a systemic skeletal disorder characterised by low bone mass and micro-architectural deterioration of bone tissue, leading to increased bone fragility and a consequent rise in fracture risk. Crucially, the bone that is present is normally mineralised — there is simply too little of it — which distinguishes osteoporosis from osteomalacia (where mineralisation is defective). It is defined operationally by a bone mineral density (BMD) T-score ≤ −2.5.
Classification & Risk Factors
Primary osteoporosis is the commonest: type I (post-menopausal) from oestrogen deficiency (predominantly trabecular bone loss, vertebral and wrist fractures) and type II (senile) of old age (cortical and trabecular loss, hip fractures). Secondary osteoporosis results from an identifiable cause. Risk factors include advancing age, female sex, early menopause, low body weight, smoking, excess alcohol, physical inactivity, family history and prolonged corticosteroid use.
Secondary cause Examples Drugs Corticosteroids (commonest), heparin, anticonvulsants, aromatase inhibitors Endocrine Cushing’s, thyrotoxicosis, hyperparathyroidism, hypogonadism GI / nutritional Malabsorption, coeliac disease, low calcium/vitamin D Others Rheumatoid arthritis, chronic kidney/liver disease, immobilisation, myeloma Clinical Features
Osteoporosis is asymptomatic until a fracture occurs — it is a ‘silent disease’. The characteristic presentations are fragility (low-trauma) fractures: of the vertebrae (progressive height loss, thoracic kyphosis ‘dowager’s hump’, and back pain), the hip (neck of femur), and the distal radius (Colles’ fracture). A fragility fracture is one occurring after a fall from standing height or less.
⚠️A fragility fracture (e.g. a hip or vertebral fracture after a minor fall, or a Colles’ fracture in a post-menopausal woman) is a red flag for osteoporosis and a strong predictor of future fractures — it should trigger assessment and treatment, not just fracture care alone.Investigations
Dual-energy X-ray absorptiometry (DEXA) measures BMD at the hip and lumbar spine and is the gold standard: a T-score ≤ −2.5 defines osteoporosis, −1 to −2.5 osteopenia. Fracture-risk tools such as FRAX combine clinical risk factors with BMD to estimate 10-year fracture probability. Radiographs show osteopenia and fractures but are insensitive to early loss. Blood tests (calcium, phosphate, alkaline phosphatase, renal, thyroid, vitamin D, and others) are typically normal in primary osteoporosis and are used to exclude secondary causes and osteomalacia.
💡In osteoporosis the biochemistry (calcium, phosphate, ALP) is normal — an important contrast with osteomalacia and hyperparathyroidism, where it is deranged. Abnormal biochemistry should prompt a search for a secondary cause or a different diagnosis.Management
Lifestyle/general: adequate dietary calcium and vitamin D, weight-bearing and resistance exercise, smoking cessation, reduced alcohol, and falls prevention. Pharmacological: bisphosphonates (alendronate, zoledronate) are first-line anti-resorptives; alternatives/additions include denosumab (RANK-ligand inhibitor), teriparatide (an anabolic PTH analogue for severe disease), and selective oestrogen-receptor modulators/HRT in selected patients. Any secondary cause is treated, and steroid-induced osteoporosis is prevented with bone protection.
Complications
The complications of osteoporosis are those of its fractures: hip fractures carry a high one-year mortality and frequently rob elderly patients of their independence; vertebral fractures cause chronic back pain, progressive kyphosis, height loss and reduced respiratory capacity; and each fracture markedly increases the risk of the next. Complications of treatment include the gastrointestinal effects of oral bisphosphonates and, rarely, atypical femoral fractures and osteonecrosis of the jaw with prolonged anti-resorptive use.
Quantity of bone is reduced but its quality of mineralisation is normal. 🔑KEY POINTS TO REMEMBER- Low bone mass with normal mineralisation → fragility; T-score ≤ −2.5 defines it.
- Primary: post-menopausal (type I, vertebra/wrist) & senile (type II, hip); many secondary causes.
- Silent until a fragility fracture (vertebra, hip, distal radius).
- DEXA is the gold standard; FRAX estimates risk; biochemistry is NORMAL in primary disease.
- Calcium/vitamin D + exercise + falls prevention; bisphosphonates first-line (denosumab, teriparatide).
📚SOURCES: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.Definition
Rickets is a disorder of the growing skeleton in which there is defective mineralisation of the growth plate (physis) and of newly formed osteoid, most often due to vitamin D deficiency. Because it affects the physis, rickets causes the characteristic bony deformities of childhood; the adult equivalent (after physeal closure) is osteomalacia.
Causes
The commonest cause is vitamin D deficiency — from inadequate sunlight exposure, poor dietary intake, or malabsorption. Other causes include renal disease (renal rickets / renal osteodystrophy), hypophosphataemic (vitamin-D-resistant) rickets (an X-linked renal phosphate-wasting disorder), and defects of vitamin D metabolism. Nutritional deficiency of calcium also contributes.
Clinical signs of rickets result from soft, poorly mineralised bone deforming under load and from swelling at the growth plates. Clinical Features
The soft, under-mineralised bones deform and the growth plates widen. Features include bow legs (genu varum) or knock knees, swelling at the wrists and ankles, the ‘rickety rosary’ (beading at the costochondral junctions), Harrison’s sulcus, frontal bossing and delayed closure of the fontanelles, delayed dentition, short stature and hypotonia. Hypocalcaemia may cause tetany or seizures in severe cases.
Investigations
Biochemistry: low or low-normal calcium, low phosphate, markedly raised alkaline phosphatase, low 25-hydroxyvitamin D, and a raised PTH (secondary hyperparathyroidism). Radiographs show characteristic changes at the metaphyses of rapidly growing bones (wrist, knee): widening, cupping, splaying and fraying of the metaphysis, with a widened growth plate and osteopenia.
💡The classic biochemical picture of nutritional rickets is low calcium, low phosphate, high alkaline phosphatase, low vitamin D and high PTH. The radiographic hallmarks are cupping, splaying and fraying of the metaphysis.Management
The mainstay is correction of the deficiency: vitamin D (as cholecalciferol/ergocalciferol, in treatment then maintenance doses) together with adequate calcium, and treatment of any underlying cause (e.g. phosphate supplements and active vitamin D analogues for hypophosphataemic rickets; management of renal disease). With biochemical and radiological monitoring, mild deformities often correct with growth; residual or severe deformity may need guided growth or corrective osteotomy once the metabolic disease is controlled.
⚠️Do not undertake corrective osteotomy while the disease is biochemically active — the deformity will recur. Normalise the biochemistry first, and reserve surgery for deformity that persists after adequate medical treatment.Site Clinical sign Skull Craniotabes, frontal bossing Chest Rachitic rosary, Harrison sulcus, pigeon chest Wrist Widening of lower radial epiphysis Legs Genu varum or valgum, sabre tibia Radiograph Cupping, fraying, splaying of metaphysis Biochemistry ↓ Ca, ↓ PO₄, ↑ ALP, ↑ PTH 🔑KEY POINTS TO REMEMBER- Defective mineralisation of the growing skeleton (physis); usually vitamin D deficiency.
- Signs: bow legs/knock knees, rickety rosary, wide wrists, Harrison’s sulcus, frontal bossing.
- Biochemistry: ↓Ca, ↓PO₄, ↑ALP, ↓vitamin D, ↑PTH.
- X-ray: cupping, splaying, fraying of the metaphysis; widened physis.
- Vitamin D + calcium (treat the cause); correct residual deformity surgically once biochemically controlled.
📚SOURCES: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.Definition
Osteomalacia is the adult equivalent of rickets: defective mineralisation of the mature bone matrix (osteoid) after the growth plates have closed. There is an excess of unmineralised osteoid, so the bone is soft and weak but not reduced in quantity — the problem is the quality (mineralisation) of bone, in contrast to osteoporosis, where the quantity is reduced but mineralisation is normal.
Causes
As with rickets, the dominant cause is vitamin D deficiency (poor sunlight, poor diet, malabsorption — e.g. coeliac disease, gastric surgery). Other causes include chronic renal failure (impaired activation of vitamin D and phosphate handling), hypophosphataemia (including tumour-induced osteomalacia), certain anticonvulsants, and rare enzyme defects.
Clinical Features
The presentation is often insidious: diffuse bone pain and tenderness (especially in the spine, pelvis and legs), proximal muscle weakness causing a waddling gait and difficulty rising from a chair or climbing stairs, and fractures/pseudofractures. Hypocalcaemia may produce paraesthesiae or tetany.
Feature Osteoporosis Osteomalacia Defect Too little bone (normal mineralisation) Poor mineralisation (normal quantity) Calcium Normal Low or low-normal Phosphate Normal Low Alkaline phosphatase Normal Raised Classic sign Fragility fracture Looser’s zones (pseudofractures) 💡The pathognomonic radiographic sign of osteomalacia is the Looser’s zone (pseudofracture / Milkman’s line) — a ribbon-like translucent band of unmineralised osteoid running perpendicular to the cortex, seen at sites such as the pubic rami, femoral neck and scapula.Investigations
Biochemistry mirrors rickets: low/low-normal calcium, low phosphate, raised alkaline phosphatase, low vitamin D and raised PTH. Radiographs show generalised osteopenia and the characteristic Looser’s zones. A bone biopsy (rarely needed) shows widened osteoid seams.
Management
Treatment is vitamin D and calcium replacement and correction of the underlying cause (e.g. treating malabsorption, phosphate supplementation, managing renal disease). Symptoms and biochemistry improve, and pseudofractures heal, with appropriate replacement. Established deformity is uncommon in adults but may require orthopaedic management.
⚠️Osteomalacia and osteoporosis can coexist and both cause fractures, but they are treated differently — checking calcium, phosphate, alkaline phosphatase and vitamin D distinguishes them and prevents giving bisphosphonates to a patient who actually needs vitamin D.Complications
Untreated osteomalacia leads to persistent bone pain, disabling proximal myopathy, and recurrent fractures and pseudofractures; hypocalcaemia can cause tetany and, rarely, seizures. In the elderly it contributes to falls and fractures and is easily overlooked as ‘osteoporosis’ unless the biochemistry is checked. With adequate vitamin D and calcium replacement the prognosis is excellent — pain resolves, muscle strength returns and pseudofractures heal.
Distinguishing Osteomalacia from Osteoporosis
Although both weaken bone and cause fractures in the elderly, the two are fundamentally different and are separated by simple biochemistry. In osteoporosis the calcium, phosphate and alkaline phosphatase are normal and the problem is a reduced quantity of normally mineralised bone; in osteomalacia the calcium and phosphate are low, the alkaline phosphatase and PTH are raised, and the vitamin D is low, reflecting defective mineralisation. Clinically, osteomalacia is distinguished by its diffuse bone pain and proximal myopathy, and radiologically by Looser’s zones — features absent in uncomplicated osteoporosis. Making this distinction matters because osteomalacia is corrected with vitamin D and calcium, not anti-resorptive drugs.
Osteoid is normal in amount but poorly mineralised — opposite of osteoporosis. 🔑KEY POINTS TO REMEMBER- Adult equivalent of rickets: defective mineralisation of mature osteoid → soft bone.
- Usually vitamin D deficiency; also renal failure, malabsorption, hypophosphataemia.
- Bone pain, proximal myopathy (waddling gait), fractures; ↓Ca, ↓PO₄, ↑ALP, ↑PTH.
- Looser’s zones (pseudofractures) are pathognomonic.
- Treat with vitamin D + calcium and the underlying cause; distinguish from osteoporosis biochemically.
📚SOURCES: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.Definition & Physiology
Parathyroid hormone (PTH) raises the serum calcium by mobilising it from bone (stimulating osteoclasts), increasing renal calcium reabsorption and phosphate excretion, and activating vitamin D. Hyperparathyroidism — excess PTH — therefore causes bone resorption and characteristic skeletal and biochemical changes. It is classified as primary, secondary or tertiary.
Type Cause Calcium PTH Primary Parathyroid adenoma (mostly)/hyperplasia High High Secondary Response to chronic hypocalcaemia (CKD, vit D deficiency) Low/normal High Tertiary Autonomous PTH after long-standing secondary High Very high Skeletal Manifestations
Excess PTH drives osteoclastic bone resorption, producing osteitis fibrosa cystica: subperiosteal bone resorption (classically along the radial borders of the phalanges), a ‘salt-and-pepper’ skull, generalised osteopenia, and brown tumours (localised osteoclastic ‘tumours’ — lytic lesions that can mimic a neoplasm and cause pathological fracture).
💡The classic clinical rhyme for primary hyperparathyroidism is ‘stones, bones, abdominal groans and psychic moans’ — renal stones, bone disease, abdominal/GI symptoms and neuropsychiatric features, all from hypercalcaemia.Renal Osteodystrophy
Renal osteodystrophy is the complex bone disease of chronic kidney disease. Failing kidneys retain phosphate and cannot activate vitamin D, causing hypocalcaemia that drives secondary hyperparathyroidism. The resulting bone disease is a mixture of osteitis fibrosa (from high PTH), osteomalacia (defective mineralisation) and osteoporosis — part of the wider ‘CKD–mineral and bone disorder’ with vascular calcification.
Investigations & Management
Biochemistry defines the type (calcium, phosphate, PTH, vitamin D, renal function, alkaline phosphatase); imaging shows subperiosteal resorption and brown tumours; localisation studies (ultrasound, sestamibi) find a parathyroid adenoma. Primary hyperparathyroidism is treated by parathyroidectomy (or monitoring if mild). Secondary/renal disease is managed medically — phosphate binders, active vitamin D analogues and calcimimetics, with control of the CKD; refractory (tertiary) disease may need parathyroidectomy.
⚠️A brown tumour is a lytic bone lesion of hyperparathyroidism that can be mistaken for a primary or metastatic tumour. Always check calcium and PTH before biopsying a lytic bone lesion — recognising hyperparathyroidism avoids an unnecessary tumour work-up.Clinical Features of Hypercalcaemia
When primary hyperparathyroidism raises the serum calcium, the patient may develop the features summarised as ‘stones, bones, abdominal groans and psychic moans’: renal stones and nephrocalcinosis and polyuria; bone pain and the changes of osteitis fibrosa; abdominal symptoms including constipation, peptic ulceration and pancreatitis; and neuropsychiatric features such as fatigue, depression, poor concentration and, when severe, confusion. Many cases today, however, are detected incidentally through a raised calcium on routine testing before symptoms appear.
Complications
The complications of hyperparathyroidism reflect both the high calcium and the bone disease: renal stones, nephrocalcinosis and progressive renal impairment; pathological fractures through brown tumours and osteitis fibrosa; peptic ulceration and pancreatitis; and, in severe hypercalcaemia, a hypercalcaemic crisis with dehydration, confusion and cardiac arrhythmia. In renal osteodystrophy the wider CKD–mineral and bone disorder brings vascular and soft-tissue calcification that contributes to the high cardiovascular mortality of chronic kidney disease, so control of phosphate and PTH is important well beyond the skeleton.
Subperiosteal erosion of the radial side of middle phalanges is classic. 🔑KEY POINTS TO REMEMBER- PTH raises calcium (bone resorption, renal Ca reabsorption, vit D activation, phosphate excretion).
- Primary (adenoma; ↑Ca ↑PTH), secondary (CKD/vit-D deficiency; ↓/normal Ca ↑PTH), tertiary (autonomous).
- Bone: osteitis fibrosa cystica — subperiosteal resorption, salt-and-pepper skull, brown tumours.
- ‘Stones, bones, groans, moans’ in primary disease.
- Primary → parathyroidectomy; renal → phosphate binders, vitamin D analogues, calcimimetics.
📚SOURCES: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.Definition
Paget’s disease of bone (osteitis deformans) is a chronic disorder of disordered, excessive bone remodelling: intense osteoclastic resorption is followed by disorganised osteoblastic new-bone formation, producing bone that is enlarged, structurally weak and deformed. It affects older adults and may involve one bone (monostotic) or many (polyostotic), commonly the pelvis, femur, tibia, skull and spine.
Clinical Features
Many cases are asymptomatic and found incidentally (a raised alkaline phosphatase or an abnormal radiograph). When symptomatic, features include bone pain, deformity (bowing of the tibia/femur — ‘sabre tibia’, an enlarging skull with increased hat size), warmth over the affected bone (from hypervascularity), and complications. Skull involvement can cause deafness (compression of the eighth nerve).
💡Suspect Paget’s in an older patient with an isolated, markedly raised alkaline phosphatase and normal calcium and phosphate, with bone pain, deformity or increasing hat size.Investigations
Biochemistry: markedly raised alkaline phosphatase (reflecting bone turnover) with normal calcium and phosphate. Radiographs show characteristic bone enlargement, coarsened trabeculae, mixed lytic and sclerotic areas, cortical thickening and bowing deformity (e.g. ‘flame-shaped’ lytic front in a long bone, ‘cotton-wool’ skull). A bone scan shows the distribution of active disease.
⚠️The most feared complication is malignant transformation to an osteosarcoma (‘Pagetic sarcoma’) — rare but very aggressive. New severe pain, a soft-tissue mass or a sudden rise in alkaline phosphatase in a patient with Paget’s must be investigated urgently.Complications & Management
Complications: bone pain, deformity, pathological fracture (often transverse ‘chalk-stick’ fractures), secondary osteoarthritis of adjacent joints, high-output cardiac failure (from hypervascular bone in extensive disease), nerve compression (deafness, spinal stenosis) and, rarely, sarcoma. Management: asymptomatic disease may just be observed; symptomatic disease is treated with bisphosphonates (which powerfully suppress the excessive turnover and relieve pain) plus analgesia, and surgery for fractures, severe deformity (osteotomy) or arthritis (joint replacement).
Pathological Phases
Paget’s disease evolves through recognised phases that explain its mixed radiographic appearance: an early osteolytic phase dominated by intense osteoclastic resorption (a well-defined advancing lytic front, e.g. ‘osteoporosis circumscripta’ in the skull or a flame-shaped front in a long bone); a mixed phase of simultaneous resorption and disorganised formation; and a late sclerotic (burnt-out) phase of dense, coarse, structurally weak bone. This disordered turnover is why the bone enlarges yet fractures and deforms so readily.
Epidemiology & Aetiology
Paget’s disease is predominantly a condition of the middle-aged and elderly, rare before 40, and shows a striking geographical and familial variation in prevalence that points to both genetic susceptibility (a family history is common; SQSTM1 mutations are implicated) and possible environmental triggers. The disordered remodelling begins with abnormally large, overactive osteoclasts, and it is this osteoclastic overactivity that bisphosphonates target so effectively, switching off the accelerated turnover, relieving pain and allowing more normal bone to be laid down.
Assessment of Disease Activity
Because alkaline phosphatase reflects the intensity of bone turnover, it is used both to gauge disease activity and to monitor the response to treatment — a fall towards normal after bisphosphonate therapy indicates suppression of the overactive remodelling. A radionuclide bone scan maps the extent and distribution of active lesions, and plain radiographs characterise individual bones, together guiding which lesions need treatment or surgical attention.
Markedly raised alkaline phosphatase with normal calcium. 🔑KEY POINTS TO REMEMBER- Disordered excessive remodelling → enlarged, weak, deformed bone; older adults.
- Often asymptomatic; bone pain, deformity (sabre tibia), warmth, skull enlargement/deafness.
- ↑↑ alkaline phosphatase with NORMAL calcium & phosphate; mixed lytic/sclerotic X-ray.
- Complications: fracture, OA, high-output cardiac failure, nerve compression, rare osteosarcoma.
- Bisphosphonates suppress turnover and relieve pain; surgery for fracture/deformity/arthritis.
📚SOURCES: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.What DEXA Measures
Dual-energy X-ray absorptiometry (DEXA / DXA) is the gold-standard investigation for measuring bone mineral density (BMD). It uses two X-ray energies to quantify the mineral content of bone, typically at the lumbar spine and proximal femur (hip), with a very low radiation dose. It is used to diagnose osteoporosis, assess fracture risk and monitor treatment.
WHO category T-score Normal ≥ −1.0 Osteopenia (low bone mass) −1.0 to −2.5 Osteoporosis ≤ −2.5 Severe (established) osteoporosis ≤ −2.5 + fragility fracture T-score vs Z-score
The T-score compares the patient’s BMD with that of a healthy young adult of the same sex (peak bone mass) and is used to diagnose osteoporosis in post-menopausal women and older men. The Z-score compares BMD with an age- and sex-matched population and is used in younger patients and children; a low Z-score suggests a secondary cause needing investigation.
💡Remember: T-score ≤ −2.5 = osteoporosis; each 1-unit fall in T-score roughly doubles fracture risk. Use the Z-score (not the T-score) in the young to flag secondary causes.Interpretation & Limitations
DEXA reports both an absolute BMD and the standardised T- and Z-scores, and is also used to monitor response to treatment over time (usually at intervals of a year or more). It has limitations: degenerative change, osteophytes, vertebral fractures, aortic calcification and previous surgery can falsely elevate spine readings in older patients, so the hip is often more reliable in the elderly, and results are always interpreted alongside clinical risk factors and, where relevant, the FRAX score rather than in isolation.
💡A practical rule: use the T-score to diagnose and treat in post-menopausal women and older men, but reach for the Z-score in younger patients and children, where a low value should prompt a hunt for a secondary cause rather than a label of simple osteoporosis.T-score compares with young adults; Z-score with age-matched peers. 🔑KEY POINTS TO REMEMBER- DEXA is the gold standard for bone mineral density (spine & hip).
- T-score ≥ −1 normal; −1 to −2.5 osteopenia; ≤ −2.5 osteoporosis.
- T-score vs young adult (diagnosis); Z-score vs age-matched (young patients/secondary causes).
- Used to diagnose, assess risk (with FRAX) and monitor treatment.
📚SOURCES: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.The Activation Pathway
Vitamin D must be activated in two hydroxylation steps before it can act. Vitamin D₃ (cholecalciferol) is synthesised in the skin from 7-dehydrocholesterol under ultraviolet (sunlight), or is taken in the diet. It is first hydroxylated in the liver to 25-hydroxyvitamin D (calcidiol) — the main storage form and the one measured to assess status — and then in the kidney by 1α-hydroxylase to the active hormone 1,25-dihydroxyvitamin D (calcitriol).
Actions & Regulation
Active calcitriol raises serum calcium and phosphate by increasing their absorption from the gut, aiding bone mineralisation and modulating bone turnover. Renal 1α-hydroxylase is stimulated by PTH and by low phosphate, linking vitamin D to calcium homeostasis.
💡Two clinically useful points: the liver makes the storage form (25-OH-D, measured clinically) and the kidney makes the active form (1,25-(OH)₂-D). Hence renal failure impairs activation and causes bone disease despite adequate intake.Clinical Relevance
Deficiency causes rickets (children) and osteomalacia (adults). Because activation is renal, chronic kidney disease causes deficiency of the active hormone (treated with active analogues such as calcitriol/alfacalcidol), whereas simple nutritional deficiency is treated with cholecalciferol.
Sources & Deficiency
The main source of vitamin D is cutaneous synthesis under sunlight, with a smaller dietary contribution (oily fish, fortified foods, egg yolk). Deficiency is therefore common where sun exposure is limited — by latitude, skin pigmentation, clothing, indoor lifestyle or institutionalisation — and in malabsorption. Because activation depends on the liver and kidney, liver and kidney disease also impair vitamin D status, which is why the active analogue (calcitriol/alfacalcidol) rather than plain vitamin D is used in renal failure.
💡The two-organ rule captures it: the liver hydroxylates to the stored, measured form (25-OH-D) and the kidney hydroxylates to the active hormone (1,25-(OH)₂-D) — which is why renal failure needs the active analogue while ordinary deficiency needs plain vitamin D.The renal 1α-hydroxylase step is the rate-limiting, PTH-regulated one. 🔑KEY POINTS TO REMEMBER- Skin (UV) or diet → liver (25-OH-D, storage/measured) → kidney (1,25-(OH)₂-D, active).
- Renal 1α-hydroxylase is stimulated by PTH; active D raises gut Ca/PO₄ absorption.
- Deficiency → rickets/osteomalacia.
- CKD impairs activation → give active analogues (calcitriol); nutritional lack → cholecalciferol.
📚SOURCES: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.Definition
Scurvy is the disease of vitamin C (ascorbic acid) deficiency. Vitamin C is essential for collagen synthesis (hydroxylation of proline and lysine), so its lack impairs the formation of collagen in bone, cartilage, blood vessels and connective tissue. Infantile scurvy (Barlow’s disease) typically appears in the second half of the first year in a child fed on processed/boiled milk without vitamin C supplementation.
Clinical Features
The hallmarks stem from defective collagen and subperiosteal haemorrhage: an irritable infant who is in pain and adopts the ‘pseudoparalysis’ (frog-leg) position (lying still because movement hurts the bleeding beneath the periosteum), bleeding gums (in the dentate child), perifollicular haemorrhages and bruising, and poor wound healing. A subperiosteal haematoma may be palpable.
Radiographic Signs & Management
Radiographs show characteristic signs: a dense ‘white line of Fränkel’ at the metaphysis, the ‘Wimberger ring’ around the epiphysis, a ‘Pelkan spur’, a scurvy (Trummerfeld) zone of rarefaction, and subperiosteal new bone from healing haemorrhage. Treatment is prompt vitamin C replacement, to which the response is rapid and complete.
💡Think of infantile scurvy in a painful, ‘pseudoparalysed’ infant with subperiosteal bleeding — the radiographic ‘ring’ (Wimberger) and dense metaphyseal ‘white line’ (Fränkel) are classic, and vitamin C is curative.Diagnosis & Prevention
The diagnosis is essentially clinical and radiographic, supported by a dietary history of inadequate vitamin C and by a low plasma ascorbic acid; the dramatic response to vitamin C is itself confirmatory. Prevention is straightforward and important — ensuring an adequate intake of fresh fruit and vegetables, and vitamin-C supplementation of infants who are fed exclusively on processed or boiled milk, which destroys the vitamin.
💡The picture to remember is a miserable infant lying in the ‘frog-leg’ pseudoparalysis from painful subperiosteal bleeding, with the radiographic ‘ring’ of Wimberger and dense ‘white line’ of Fränkel — and a swift, complete recovery on vitamin C.Pain from subperiosteal bleeding causes the pseudoparalysis. 🔑KEY POINTS TO REMEMBER- Vitamin C deficiency → defective collagen; infantile form = Barlow’s disease.
- Painful pseudoparalysis (frog-leg), subperiosteal haemorrhage, bleeding gums, bruising.
- X-ray: white line of Fränkel, Wimberger ring, Pelkan spur, scurvy zone.
- Rapid, complete response to vitamin C.
📚SOURCES: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.Definition
Skeletal fluorosis is a chronic metabolic bone disease caused by excessive intake of fluoride, most commonly from drinking water with a high fluoride content (endemic in parts of India and other regions). Fluoride is deposited in bone as calcium fluorapatite, causing increased but disorganised, dense and brittle bone, along with calcification of ligaments and entheses.
Clinical Features
The earliest and most familiar sign is dental fluorosis (mottling and brown staining of the enamel) in those exposed during tooth development. Skeletal disease produces bone and joint pain and stiffness, especially of the spine, with progressive restriction of movement. Advanced disease causes ossification of ligaments (including the spinal and interosseous ligaments), kyphosis and a rigid spine, and neurological deficit from spinal canal stenosis / cord compression.
⚠️In endemic regions, skeletal fluorosis is an important cause of a stiff, painful spine and of compressive myelopathy from ossified spinal ligaments and canal stenosis — it should be considered in patients from such areas with these features.Investigations & Management
Radiographs show increased bone density (osteosclerosis), coarse trabeculation, and calcification/ossification of ligaments and interosseous membranes (e.g. between radius and ulna); raised urinary and serum fluoride confirm exposure. Management centres on removing the source of fluoride (safe drinking water, defluoridation), nutritional support (adequate calcium and vitamin C/D), and surgical decompression for neurological compression from stenosis.
Types & Prevention
Fluorosis is described in three overlapping forms: dental (mottled enamel from exposure during tooth development), skeletal (osteosclerosis, ligament ossification, spinal disease) and non-skeletal (non-specific gastrointestinal and general symptoms). It is fundamentally a preventable, public-health problem: the definitive measure is provision of drinking water within safe fluoride limits (defluoridation, alternative water sources) in endemic areas, alongside nutritional support, making it an important community-medicine as well as orthopaedic condition.
Endemic in parts of India where groundwater fluoride is high. 🔑KEY POINTS TO REMEMBER- Chronic fluoride excess (usually high-fluoride drinking water; endemic in parts of India).
- Dental mottling; then bone/joint pain, spinal stiffness; ligament ossification & canal stenosis.
- X-ray: osteosclerosis + calcified ligaments/interosseous membrane; ↑ fluoride levels.
- Remove the fluoride source (safe water); decompress neurological compression surgically.
📚SOURCES: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.Definition
Osteogenesis imperfecta (OI, ‘brittle bone disease’) is a hereditary disorder of type I collagen (usually autosomal dominant) that makes bone abnormally fragile and prone to fracture from minimal trauma. Because type I collagen is widespread, the disease also affects other connective tissues.
Clinical Features
The cardinal feature is recurrent fractures with minimal trauma, leading to deformity and short stature. Associated features reflect defective collagen: blue sclerae, dentinogenesis imperfecta (fragile, discoloured teeth), hearing loss (otosclerosis), ligamentous laxity and easy bruising. Severity ranges from lethal perinatal forms to mild disease with only a few fractures (Sillence classification).
⚠️The multiple fractures of osteogenesis imperfecta at different stages of healing can be mistaken for non-accidental injury (and vice versa). Blue sclerae, family history, dentinogenesis imperfecta and the fracture pattern help distinguish them — a careful, non-judgemental assessment is essential.Management
There is no cure; management is supportive and multidisciplinary: prompt fracture care (with awareness that bones are fragile), bisphosphonates (which reduce fracture rate and bone pain), physiotherapy and mobility aids, and surgery including intramedullary rodding of long bones (telescoping rods) to control recurrent fractures and deformity. Genetic counselling is offered.
Pathophysiology & Classification
Most cases result from mutations in the COL1A1/COL1A2 genes that encode type I collagen, producing either too little normal collagen or abnormal collagen. The Sillence classification grades severity from type I (mild, blue sclerae, few fractures, near-normal stature) through the perinatally lethal type II, to the severe deforming types III and IV. This spectrum explains why presentation ranges from a stillborn infant with multiple fractures to an adult with only mildly brittle bones and blue sclerae.
💡The clinical shorthand is brittle bones + blue sclerae + brittle teeth (± deafness) from a type I collagen defect; bisphosphonates and intramedullary rodding are the mainstays that reduce fractures and control deformity.Blue sclerae with recurrent fractures in a child raises the diagnosis. 🔑KEY POINTS TO REMEMBER- Hereditary (usually AD) defect of type I collagen → fragile bones.
- Recurrent low-trauma fractures, deformity, blue sclerae, brittle teeth, hearing loss.
- Beware confusion with non-accidental injury (and vice versa).
- Bisphosphonates + supportive care; intramedullary rodding for recurrent long-bone fractures.
📚SOURCES: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.Definition
Osteopetrosis (‘marble bone disease’) is a rare hereditary disorder of defective osteoclast function: because osteoclasts cannot resorb bone, bone is laid down but not remodelled, so it becomes abnormally dense but brittle. The paradox is that this very dense bone fractures easily and is mechanically weak.
Clinical Features
Severe (infantile, autosomal-recessive) forms present early with bone marrow failure (anaemia, infections, bleeding — because dense bone crowds out the marrow), cranial nerve compression (blindness, deafness) from narrowed foramina, hepatosplenomegaly (extramedullary haematopoiesis) and failure to thrive. The milder (adult, autosomal-dominant / Albers-Schönberg) form may present with fractures or be found incidentally.
💡Radiographs show strikingly dense (sclerotic) bones, loss of the corticomedullary distinction, and classic signs such as the ‘bone-within-bone’ appearance and ‘sandwich vertebra’ (dense endplates). Despite the density, the bone is brittle.Management
The milder adult form needs mainly supportive care and fracture management. The severe infantile form is life-threatening and may be treated with haematopoietic stem-cell transplantation (which provides functional osteoclasts), together with management of the marrow failure and complications.
Complications
The consequences of unremodelled, marrow-crowding bone dominate the severe form: progressive anaemia, thrombocytopenia and immunodeficiency from marrow failure, with compensatory hepatosplenomegaly; cranial nerve palsies (optic and facial nerves, deafness) as skull foramina narrow; and, throughout the skeleton, fractures that heal poorly and osteomyelitis (classically of the mandible) because the dense, poorly vascularised bone resists infection clearance.
💡The paradox is the whole point: osteoclasts fail, so bone is dense on X-ray yet brittle and marrow-poor — explaining the combination of fractures and marrow failure, and why a stem-cell transplant (supplying functional osteoclasts) can cure the severe form.Bones are dense yet brittle — they fracture easily. 🔑KEY POINTS TO REMEMBER- Defective osteoclast resorption → dense but brittle bone (‘marble bone’).
- Severe infantile form: marrow failure, cranial nerve compression, failure to thrive.
- X-ray: very dense bones, ‘bone-within-bone’, sandwich vertebra; still fractures easily.
- Adult form supportive; severe infantile form may need stem-cell transplant.
📚SOURCES: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.Definition
Achondroplasia is the commonest form of short-limbed (disproportionate) dwarfism. It is an autosomal-dominant disorder (most cases arising as new mutations, associated with advanced paternal age) caused by a mutation in the FGFR3 gene that inhibits endochondral ossification at the growth plate — so the long bones, which grow by endochondral ossification, are short, while membranous bone growth is relatively normal.
Clinical Features
There is disproportionate short stature with short proximal (rhizomelic) limbs, a relatively normal-length trunk, and a large head with frontal bossing and midface hypoplasia. The hands show a ‘trident’ configuration, and there is often genu varum and an exaggerated lumbar lordosis. Intelligence and life expectancy are usually normal.
⚠️Foramen magnum and spinal stenosis are important complications of achondroplasia: foramen magnum narrowing can cause cord/brainstem compression (and even sudden death) in infants, and lumbar canal stenosis commonly causes symptoms in adults — both may need surgical decompression.Management
Management is supportive and multidisciplinary: monitoring growth and development, anticipating and treating complications (foramen magnum stenosis, spinal stenosis, hydrocephalus, recurrent otitis media, genu varum), and orthopaedic correction of deformity or decompression of stenosis as needed. Genetic counselling is provided; targeted therapies (FGFR3-pathway agents) are emerging.
Genetics & Inheritance
Achondroplasia is autosomal dominant, but around 80% of cases are new (sporadic) mutations in the FGFR3 gene, associated with advanced paternal age; an affected parent has a 50% chance of transmitting it. The FGFR3 mutation is a gain-of-function change that over-inhibits chondrocyte proliferation at the growth plate, restricting the endochondral bone growth responsible for long-bone length while sparing membranous (skull vault) growth, which explains the disproportionate phenotype.
💡Recognise achondroplasia by rhizomelic (proximal) limb shortening with a normal-length trunk, frontal bossing and midface hypoplasia in a child of normal intelligence — and stay alert to foramen magnum and spinal canal stenosis, the complications that actually cause harm.Membranous ossification is normal, so the skull vault and trunk are spared. 🔑KEY POINTS TO REMEMBER- Commonest short-limbed dwarfism; AD, FGFR3 mutation impairing endochondral ossification.
- Rhizomelic short limbs, normal trunk, frontal bossing, midface hypoplasia, trident hand.
- Normal intelligence & lifespan; watch for foramen magnum & spinal (canal) stenosis.
- Supportive multidisciplinary care; decompress stenosis and correct deformity as needed.
📚SOURCES: Maheshwari's Essential Orthopaedics; Apley & Solomon's System of Orthopaedics and Trauma; AO Principles of Fracture Management.