﻿ Miscellaneous Lesions - AAOS Comprehensive Orthopaedic Review ﻿

AAOS Comprehensive Orthopaedic Review

Section 4 - Orthopaedic Oncology and Systemic Disease

Chapter 42. Miscellaneous Lesions

I. Melorheostosis

A. Definition and demographics


1. Melorheostosis is a rare, painful disorder of the extremities characterized by large amounts of periosteal new bone formation occurring on the surface of multiple bones.


2. No sex predilection


3. Usually discovered by age 40 years


B. Genetics/etiology


1. Nonhereditary


2. Often follows sclerotomal pattern


C. Clinical presentation




1. Pain, reduced range of motion, contractures


2. Soft tissues—tense, erythematous skin, induration and fibrosis of subcutaneous tissue


D. Radiographic appearance (

Figure 1)


1. More common in the lower extremity and usually involves one extremity


2. Cortical hyperostosis ("dripping candle wax")


3. Wavy appearance that flows across and involves joints


E. Pathology


1. Enlarged bony trabeculae


2. Normal haversian systems


F. Treatment


1. Symptomatic treatment of pain


2. Occasionally, correction of contractures by excision of hyperostotic and fibrotic areas


[Figure 1. Melorheostasis. A, AP view of the knee showing periosteal new bone formation on the lateral aspect of the joint. Note the nodular appearance of the heavily ossified bone formation. B, Lateral view of the knee showing the large amount of nodular bone formation arising from the posterior aspect of the distal femur. C, T2-weighted coronal image of the knee showing very low signal nodular masses (corresponding to bone formation) and high signal changes (corresponding to edema) around the nodules.]

II. Massive Osteolysis

A. Definition and demographics


1. Massive osteolysis, also called Gorham disease or vanishing bone disease, is a very rare condition that is characterized by massive resorption of entire segments of bone.


2. Affects both sexes


3. Most common in patients younger than 40 years


B. Etiology/clinical presentation


1. May be related to trauma


2. Abrupt or insidious onset


C. Radiographic appearance


1. Massive osteolysis


2. Progressive lytic bone loss


3. End of the remaining bone is often tapered


4. Often spreads to adjacent bones (crosses joints)


D. Pathology/treatment


1. Begins with numerous vascular channels and ends with fibrosis


2. No effective treatment

III. Gaucher Disease

A. Definition and demographics


1. Gaucher disease is an enzyme deficiency that causes accumulation of glucocerebrosides in the marrow, leading to bone deformities and osteonecrosis.


2. Most common in Ashkenazi Jews


B. Genetics/etiology


1. Autosomal recessive


2. Caused by deficiency of glucocerebrosidase (acid β-glucosidase, lysosomal enzyme)


C. Clinical presentation


1. Types


a. Type I: adult nonneuropathic


b. Type II: acute neuropathic (infants)—lethal form


c. Type III: juvenile subacute neuropathic (children)—death by second decade of life


2. Hematologic problems—pancytopenia, thrombocytopenia



Figure 2. Gaucher disease. A, AP view of the tibia showing sclerosis in the medullary cavity. B, AP view of the distal femur showing the Erlenmeyer flask deformity, typical of Gaucher disease. Note the widened metaphyses.]

3. Easy bruisability, fatigue


4. Bone problems


a. Osteonecrosis


b. Fractures


D. Radiographic appearance (Figure 2)


1. Abnormal bone remodeling—Erlenmeyer flask deformity


2. Lucent expansile lesions


3. Subchondral collapse


4. Vertebral collapse


E. Pathology/treatment


1. Macrophages are enlarged and filled with abnormal material (crumpled cytoplasm).


2. Periodic acid-Schiff (PAS)-positive, acid phosphatase-positive


3. Treatment is enzyme replacement.

IV. Stress Fractures

A. Definition and demographics


1. Stress fractures are overuse injuries in which normal bone is subjected to abnormal stresses, resulting in microfractures.


2. Stress fractures occur following repetitive stress in either normal or abnormal bone.


a. Fatigue fracture—Occurs in normal bone, such as in military recruits following marching



Figure 3. Coronal CT reconstruction of the proximal femur in a patient with a stress fracture. Note the focal endosteal new bone formation and the periosteal new bone formation on the medial femoral cortex.]

   (therefore sometimes called a march fracture).


b. Insufficiency fracture—Occurs in abnormal bone, such as in pagetic patients with femoral shaft bowing.


3. Common in young, athletic patients


B. Etiology/clinical presentation


1. Linear microfractures in trabecular bone from repetitive loading


2. Pain during activity located directly over the involved bone


C. Imaging appearance


1. Radiographs/CT


a. Diaphysis


i. Linear cortical radiolucency


ii. Endosteal thickening


iii. Periosteal reaction and cortical thickening


b. Metaphysis: focal linear increased mineralization (condensation of the trabecular bone)


c. Endosteal and periosteal new bone formation (Figure 3)


2. Technetium Tc 99m bone scan—Area of focal up-take in cortical and/or trabecular region.


3. MRI (

Figure 4)


a. Periosteal high signal on T2-weighted images (earliest finding)


[Figure 4. Stress fracture. A, Coronal T2-weighted MRI showing high signal in the medullary cavity and on the periosteal surface. B, Axial T2-weighted MRI showing high signal in the medullary cavity and over the posteromedial cortical surface of the tibia.]

b. Linear zone of low signal on T1-weighted images


c. Broad area of increased signal on T2-weighted images


d. When a stress fracture is advanced in clinical course, linear low signal lines representing the fracture may be seen.


D. Pathology


1. Callus formation


2. Woven new bone


3. Enchondral bone formation


E. Treatment


1. Rest


2. Protected weight bearing until the fracture heals


3. Prophylactic fixation in selected cases


a. Tension-side femoral neck fractures in athletes


b. Patients with low bone mass, especially patients older than 60 years

V. Neuropathic Arthropathy

A. Definition and demographics


1. Neuropathic arthropathy is the destruction of a joint following loss of protective sensation.



Figure 5. Neuropathic arthropathy. A, Lateral radiograph of the elbow in a patient with syringomyelia. There are very prominent neuropathic changes with complete destruction of the articular surfaces. B, Lateral radiograph of the ankle in a patient with diabetes mellitus. Note the complete destruction of the articular surfaces with dissolution and fragmentation.]

2. Common locations include the foot, ankle, elbow, and shoulder.


B. Etiology—Disease processes that damage sensory nerves.


1. Diabetes mellitus: affects the foot and ankle


2. Syringomyelia: affects the shoulder and elbow


3. Syphilis: affects the knee


4. Spinal cord tumors: affect the lower extremity joints


C. Clinical presentation


1. Swollen, warm, and erythematous joint with little or no pain


2. Often mimics infection, especially in patients with diabetes


D. Radiographic appearance (Figure 5)


1. Characteristic features: destruction of the joint


2. Initial changes may simulate osteoarthritis


3. Late changes


a. Fragmentation of the joint


b. Subluxation/dislocation


c. Fracture


d. Collapse


E. Pathology


1. Productive/hypertrophic changes secondary to the following spinal cord lesions (generally do not involve the sympathetic nervous system)


a. Spinal cord traumatic injury


b. Neoplasms


c. Spinal cord malformations


d. Syphilis


e. Syringomyelia


2. Destructive/atrophic changes usually secondary to peripheral nerve damage. Conditions that cause atrophic changes:


a. Diabetes


b. Alcoholism


3. Histologic changes


a. Synovial hypertrophy


b. Fragments of bone and cartilage in the synovium (detritic synovitis)


F. Treatment


1. Rest, elevation, protected weight bearing


2. Total contact casting when ulcers are present in the foot and ankle

VI. Hemophilic Arthropathy

A. Definition and demographics


1. Hemophilic arthropathy is the destruction of a joint secondary to repetitive bleeding into the synovial cavity.


2. Classic hemophilia (hemophilia A) is caused by a deficiency of factor VIII; Christmas disease (hemophilia B) is caused by a deficiency of factor IX.


3. Locations: knee, ankle, elbow


B. Genetics/etiology—X-linked recessive.


C. Clinical presentation


1. Hemarthrosis—Often in young males, 3 to 15 years of age.


2. Temporal changes


a. Acute hemarthrosis: tense, painful effusion


b. Subacute hemarthrosis: occurs after two previous bleeds


c. Chronic hemarthrosis: arthritis, contractures


D. Radiographic appearance


1. Arnold/Hilgartner stages


a. Stage I: soft-tissue swelling


b. Stage II: osteoporosis


c. Stage III: bone changes (subchondral cysts) with intact joint


d. Stage IV: cartilage loss


e. Stage V: severe arthritic changes


2. Radiographic changes


a. Knee


i. Overgrowth of distal femur and proximal tibia


ii. Distal condylar surface appears flattened


iii. Squaring of the inferior portion of the patella


b. Ankle: arthritic changes of the tibiotalar joint


c. Elbow: arthritic changes and contractures


E. Pathology/treatment


1. Synovial hypertrophy and hyperplasia


2. Synovium covers and destroys the cartilage.


3. Treatment is prophylaxis against recurrent hemarthroses.

Top Testing Facts

1. Melorheostosis is characterized by nodular, heavily mineralized bone on the surface of bones and in the soft tissues, which gives a "dripping candle wax" appearance on radiographs.


2. Massive osteolysis is purely lytic resorption of large segments of bone.


3. Radiographic findings for Gaucher disease include Erlenmeyer flask deformity (widened metaphyses).


4. Gaucher disease is caused by a deficiency of the enzyme glucocerebrosidase (acid β-glucosidase, lysosomal enzyme); treatment consists of enzyme replacement.


5. Imaging findings for stress fractures—radiographs: periosteal new bone formation; T1-weighted MRI: normal marrow except for low signal linear areas; T2-weighted MRI: high signal in the medullary cavity and on the periosteal surface.


6. Neuropathic arthropathy—remember the common locations by disease state: syringomyelia—shoulder and elbow; syphilis—knee; and diabetes—foot and ankle.


7. Radiographic findings for neuropathic arthropathy include fragmentation, subluxation, and dissolution of the joint.


8. Hemophilic arthropathy—remember the factor deficiencies (hemophilia A—factor VIII, hemophilia B—factor IX), and remember the key radiographic findings (knee—squaring of the inferior patellar pole and femoral condyles).


McCarthy EF, Frassica FJ: Genetic diseases of bones and joints, in Pathology of Bone and Joint Disorders. Philadelphia, PA, Saunders, 1998, pp 54-55.

Resnick D: Neuropathic osteoarthropathy, in Diagnosis of Bone and Joint Disorders, ed 3. Philadelphia, PA, Saunders, 1995, pp 3413-3442.

Resnick D, Niwayama G: Enostosis, hyperostosis, and periostitis, in Diagnosis of Bone and Joint Disorders, ed 3. Philadelphia, PA, Saunders, 1995, pp 4410-4416.

Resnick D, Niwayama G: Osteolysis and chondrolysis, in Diagnosis of Bone and Joint Disorders, ed 3. Philadelphia, PA, Saunders, 1995, pp 4475-4476.

Siris ES, Roodman GD: Paget's disease of bone, in Primer on the Metabolic Bone Diseases and Disorders of Mineral Metabolism, ed 6. Washington, DC, American Society for Bone and Mineral Metabolism, 2006, pp 320-329.

Vigorita VJ: Osteonecrosis, Gaucher's disease, in Orthopaedic Pathology. Philadelphia, PA, Lippincott Williams & Wilkins, 1999, pp 503-505.