Osteochondroses

Updated: Dec 12, 2017
  • Author: Manish Kumar Varshney, MBBS, MRCS; Chief Editor: Harris Gellman, MD  more...
  • Print
Overview

Background

Osteochondrosis is a self-limiting developmental derangement of normal bone growth, primarily involving the centers of ossification in the epiphysis. [1, 2]  It usually begins in childhood as a degenerative or necrotic condition. By definition, osteochondrosis is an aseptic ischemic necrosis. Central to the definition is the prerequisite that the epiphysis should have been normal. There is little controversy regarding this requirement, but it is difficult to prove that an epiphysis was normal.

Conditions affecting various sites have been crudely grouped together under the term osteochondrosis. This categorization is primarily based on the morphologic and evolutionary similarities of the involved sites, as seen on radiographs. In broad terms, osteochondroses are a heterogeneous group of unrelated lesions that share the following characteristics:

  • Predilection for affecting the immature skeleton
  • Involvement of the epiphysis
  • Apophysis or epiphysioid bone
  • Radiographic picture dominated by fragmentation, collapse, sclerosis, and reossification of osseous centers

Practically all of the epiphyses can be affected. Involved sites typically possess many of the features of ischemic necrosis, both radiologically and histologically.

It is prudent to speak of necrosis rather than avascular necrosis because even though ischemia prevails, vessels are present. The vascular theory is controversial because entities such as Blount disease and Scheuermann disease do not lead to ischemic changes and because trauma is implicated as the mechanism for a number of afflictions. However, the ischemic theory should not be abandoned yet, because investigations have led investigators to a renewed focus on various coagulation-related factors and vascular involvement as the primary culprits.

A key issue in discussing osteochondroses is that the terminology has become increasingly confusing. The term syndrome may be generally preferable to the term disease because it arguably incorporates both the radiographic patterns and the clinical presentations. Some of these conditions, such as Sever disease and Van Neck disease, may be more appropriately referred to as phenomena. In view of the evolving nature of the nomenclature, all three terms—disease, syndrome, and phenomenon—will be used in this article (see Pathophysiology, Classification, below).

Although some clinicians include osteochondritis dissecans among the osteochondroses, this inclusion is controversial. Strictly defined, osteochondritis dissecans is not primarily a disease process involving growth center, and it occurs in adults as well as children. The juvenile form of this process may represent focal ischemic involvement, and only this form should be considered an osteochondrosis. [3]

The inclusion of posttraumatic osteonecrosis and normal variants of ossification in an expanded classification of osteochondroses has also been controversial. As our knowledge of these conditions has grown, it has proved possible to establish their etiologic bases. In the authors’ view, morphologically similar but etiologically unrelated conditions should not be combined in the same group.

Next:

Pathophysiology

Pathogenesis

The initial events in the pathogenesis of osteochondrosis remain elusive, but clinical and radiologic evidence points to ischemic necrosis of the ossification center. This process could be due to a primary vascular event, a definite traumatic event, or multiple additive traumas.

The osteochondrotic process is essentially degeneration of the epiphyseal osseous nucleus. This process is almost certainly due to either (1) interference with the blood supply, which leads to necrosis of the cartilage-canal vessels in the subchondral bone and adjacent epiphysis, or (2) failure of the bony centrum to enlarge and disordered proliferation of the cartilaginous cells in the epiphysis. Secondary changes (eg, fragmentation, collapse, and sequestrum formation) develop in accordance with the characteristics of the affected region.

The disease process can be sequential or simultaneous. It can involve a single epiphysis (isolated disease) or several (multiple-site disease), and not even the sesamoids are spared (as in Sinding-Larsen syndrome and involvement of first metatarsal sesamoids). The underlying processes seem to be essentially the same for isolated and multiple-site disease. However, presentations may vary, depending on the stresses and strains to which the epiphyses have been subjected. The efficacy of regeneration and repair determines the patient’s long-term clinical outcome.

With complete healing, little lasting harm is done. However, partial healing or failure to heal becomes a source of chronic pain and disability later in life. Accordingly, the physician must be vigilant to avoid overlooking an osteochondrosis in a pediatric patient.

Ponseti proposed that the following features are common to all osteochondroses:

  • Uncertain etiology
  • Clinical pattern of progression
  • Radiologic appearance of ischemic necrosis

Duthie and Houghton proposed the following models for the development of osteochondroses:

  • Normal epiphysis subjected to extreme trauma (eg, pitcher’s elbow with osteochondritis dissecans of the capitellum)
  • Mildly dyschondrotic epiphysis subjected to more-than-usual stress (eg, Perthes disease)
  • Severely affected dyschondrotic epiphysis subjected to normal stress (eg, the capital femoral epiphysis in Gaucher disease)

Other proposed pathogenetic factors for which further study is warranted include an altered collagen-to-proteoglycan ratio, [4] biochemical abnormalities (eg, altered expression of matrix metalloproteinases [MMPs] such as MMP-1, MMP-3, and MMP-13 [5] ), and overexpression of glycosaminoglycans and aggrecan as a consequence of altered mechanics that exacerbate damage to the cartilage.

Classification

Earlier classifications of osteochondroses divided them into pressure, traction, and atavistic types (Burrows’s classification) or into compression, tension, and atavistic types (Goff’s classification). These systems were inadequate. Siffer proposed a classification that divided osteochondroses into articular, nonarticular, and physeal types; this schema is largely accepted today.

Articular osteochondroses exhibit the following characteristics:

  • Primary involvement of the articular and epiphyseal cartilage and a subjacent endochondral ossification center – Freiberg disease [6]
  • Secondary involvement of the articular and epiphyseal cartilage as a consequence of ischemic necrosis of subjacent bone – Perthes disease, Köhler disease, osteochondritis dissecans

Nonarticular osteochondroses occur at the following locations:

  • Tendinous attachments - Osgood-Schlatter syndrome, Monde-Felix disease
  • Ligamentous attachments - Vertebral ring
  • Impact sites - Sever disease

Physeal osteochondroses involve the following:

  • Long bones – Tibia vara (Blount disease)
  • Scheuermann disease

The use of eponyms for the osteochondroses is so deeply ingrained in the literature that any discussion of these syndromes would be incomplete without the mention of these terms (see Table 1 below).

Table 1. Eponyms for Osteochondroses (Open Table in a new window)

Center Location Eponym
Primary Carpal scaphoid Preiser disease [7]
Lunate Kienböck disease
Medial cuneiform Buschke disease
Patella Köhler disease
Talus Mouchet disease
Tarsal scaphoid Köhler disease
Vertebral body Calvé disease (Legg-Calve-Perthes Disease)
Secondary Vertebral epiphysis Scheuermann disease and Scheuermann kyphosis
Iliac crest Buchman disease
Symphysis pubis Pierson disease
Ischiopubic junction Van Neck disease or phenomenon
Ischial tuberosity Valtancoli disease
Calcaneal apophysis Sever disease or phenomenon
Accessory tarsal navicular or os tibiale externum Haglund disease
Second metatarsal Freiberg disease (or Freiberg infarction)
Fifth metatarsal base Iselin disease
Talus Diaz disease
Distal tibial epiphysis Lewin disease
Proximal tibial epiphysis Blount disease [8]
Tuberosity of the tibia Osgood-Schlatter disease
Secondary patellar center Sinding-Larsen-Johansson syndrome (Sinding-Larsen disease, jumper’s knee)
Lesser trochanter of the femur Monde-Felix disease
Greater trochanter of the femur Mandl or Buchman disease
Capital epiphysis of the femur Legg-Calve-Perthes disease
Phalanges Thiemann syndrome
Metacarpal heads Mauclaire disease
Proximal epiphysis of the radius Schaefer disease
Distal epiphysis of the ulna Burns disease
Medial humeral condyle Froelich disease
Lateral humeral condyle Froelich disease
Capitellum of the humerus Panner disease (see Little League Elbow Syndrome)
Humeral head Hass disease
Clavicle Friedrich disease

Associated disorders

Various investigators have found that major genitourinary disorders are associated with Perthes disease. The risk of inguinal hernia increases 8 times in patients with this disease. Slippage of the capital femoral epiphysis may occur in patients with Scheuermann disease.

Considerable attention has been directed toward the occurrence of growth retardation with osteochondroses. Substantiating evidence for this association includes reduced excretion of urinary deoxypyridinoline and glycosaminoglycans, as well as low plasma levels of insulinlike growth factor (IGF)-1. These changes cause a disturbance in the metabolism of collagen. [9] In the future, this alteration may be linked to the pathogenesis of osteochondrosis in syndromic terms.

Previous
Next:

Etiology

Osteochondroses should generally be thought of as syndromes rather than diseases because multiple causes—some indeterminable—may be involved. Accordingly, the etiology is largely a matter of hypothesis. The main concern is to identify any distinct pathologic condition present that may be controlled or even corrected with proper therapy.

Probable causes

Various factors have been proposed as potential causes of osteochondroses. The oldest, most controversial, and therefore least widely accepted of these are social deprivation, dietary deficiency, and passive exposure to smoke (an unknown industrial factor). The studies that proposed these factors as causes were geographically specific, and their results might have been confounded by the etiologic fallacy.

The factors currently accepted as the most probable causes of osteochondrosis—alone or in various combinations (in multifactorial disease)—are these:

  • Genetic predisposition [10]
  • Environmental factors
  • Thrombotic predisposition
  • Acute or repeated trauma
  • Embolism
  • Copper (trace element) deficiency
  • Infection
  • Mechanical factors

With respect to genetic predisposition, Blount disease is known to be inherited in an autosomal dominant pattern; however, inheritance patterns of other potentially inheritable disorders (eg, Scheuermann disease [11] ) remain to be characterized.

An area deserving of further study is the genetic predisposition that produces a hypercoagulable state due to a deficiency in tissue factor pathway inhibitor (TFPI). [12] Others include fibrinolysis defects involving protein S, protein C deficiency, [13] and resistance to activated protein C. Likewise, there is no consensus regarding the inheritable disorders of thrombophilia due to mutations in the genes for prothrombin (mutation G20210A), factor V Leiden (mutation G1691A), methylene tetrahydrofolate reductase (C677T mutation), or anticardiolipin antibodies. [14, 15]

With respect to both genetic predisposition and environmental factors, exposure to second-hand smoke may be related to the development of Perthes disease as a consequence of the G-455-A polymorphism of the beta-fibrinogen gene.

Deficiencies in trace elements (eg, copper and zinc) have been proposed as probable causes on the basis of animal studies. [16]

Infection, which at one time appeared to have been unanimously discredited as a cause of osteochondrosis, has now been shown to trigger or potentiate the disease process. Its effect may be direct or related to autoimmune mechanisms.

Individual mechanical factors may be related to the development of specific diseases, such as Osgood-Schlatter [17, 18] disease and Sinding-Larsen-Johansson disease. Examples of such factors are a long patella (Grelsamer type II) and extensor apparatus and external tibial torsion. Various authors have suggested that Osgood-Schlatter syndrome is traumatic in origin and that it does not involve ischemic necrosis.

Compounding factors

Compounding factors associated with osteochondrosis have also been identified. These include hormonal imbalance (hypothyroidism), sickle cell anemia, Gaucher disease and mucopolysaccharidoses, tetany due to magnesium deficiency, and cystic fibrosis, among others. However, all of these conditions are now well-established diseases on their own and, in the authors’ view, should not be linked with osteochondroses.

Previous
Next:

Epidemiology

The frequency with which osteochondroses affect different sites varies. Because they are self-limiting disorders, they often go undiagnosed; consequently, exact documentation is difficult. Perthes disease is considered to be the most common disabling osteochondrosis, but it is not the most common of all osteochondroses. Some osteochondroses occur so infrequently that a physician may never encounter them in his or her whole period of practice.

Age-related demographics

Most osteochondroses occur shortly after the bony nucleus appears, around the middle of the growth spurt. At this time, the epiphysis is mainly cartilaginous and growing rapidly; therefore, it is susceptible to injury. Exceptions to this general statement include osteochondritis dissecans, Scheuermann disease, and Osgood-Schlatter disease, which predominantly occur during the adolescent growth spurt.

Sex-related demographics

Freiberg disease is more common among females than among males, and juvenile osteochondritis dissecans of the elbow (capitellum) is common among female javelin throwers. All other osteochondroses occur most frequently in males. The delayed appearance and maturation of the growth center in boys may account for this difference. In addition, the high activity level further traumatizes the immature epiphysis.

Race-related demographics

Some of the common and well-studied osteochondroses have definite racial and ethnic differences in incidence and prevalence. For example, Perthes disease is uncommon among persons of African or Chinese descent, whereas Blount disease is common in Africa but uncommon in Western Europe and North America.

Previous
Next:

Prognosis

Because osteochondrosis is a self-limiting disorder, the outcome is usually good. [19]  More often than not, in fact, the syndrome goes unnoticed. However, when osteochondrosis does not remit with conservative treatment or surgery, the patient’s prognosis is usually poor. In these cases, patients may need salvage interventions or joint replacement later in life to manage secondary changes. Patients should be properly informed and educated before such interventions are undertaken.

Previous