Osteochondropathy: What it is and what causes it

Osteochondropathies are a group of diseases of bone and cartilage growth and remodeling that affect the epiphyses and subchondral bone, as well as tendon attachment sites in growing patients. Classic forms include osteochondritis dissecans, Osgood-Schlatter disease, Legg-Calve-Perthes disease, Sever's disease, Freiberg disease, and other rare osteochondroses. The common mechanism is usually localized ischemia of the subchondral bone or overload of immature growth plates, resulting in pain, swelling, limited function, and risk of joint deformity. [1]

Terminologically, it is important to distinguish between epiphyseal osteochondrosis and traction apophysitis. The former is associated with damage to the subchondral bone beneath the articular cartilage and can lead to unstable osteochondral fragments. The latter is caused by repeated tendon traction on the immature apophysis and is usually reversible with load correction. This distinction influences diagnosis and treatment decisions, as the prognosis and treatment options differ fundamentally. [2]

Modern approaches are based on early detection, stratification by lesion stability and age of skeletal maturation, and a stepwise approach, ranging from load modification and physical therapy to organ-preserving surgical techniques for fragment instability. Timely management reduces the risk of early osteoarthritis and improves long-term outcomes. [3]

Epidemiology

The incidence of various osteochondropathy depends on age and activity. Osgood-Schlatter disease is one of the most common causes of anterior knee pain in athletically active adolescents. Osteochondritis dissecans of the knee occurs in children and adolescents, less commonly in adults, and, according to population surveys, is estimated to occur in tens of cases per 100,000 adolescents. [4]

Legg-Calvé-Perthes disease typically affects children around age 50 and is considered a rare disorder. Recent reviews note a possible decline in incidence in some countries, attributed to changes in early detection and lifestyle factors, although data remain mixed. [5]

Traction apophysitis, including Sever's disease and Sinding-Larsen-Johansson syndrome, are more commonly seen in young athletes during periods of intense growth, particularly with jumping and running activities. The contribution of repetitive, cyclical sports has been confirmed in recent reviews of the lower extremity in young athletes. [6]

Reasons

The etiology of osteochondropathy is multifactorial. Osteochondritis dissecans is thought to involve impaired microcirculation of the subchondral bone, followed by instability of the osteochondral plate. Overuse and repeated microtrauma exacerbate the process, which is especially significant with high training volumes. [7]

Traction apophysitis is caused by repeated tendon strain on immature attachment sites, leading to microtrauma to the apophysis and a local inflammatory response. These conditions are usually reversible with load correction and adequate rehabilitation. [8]

In Legg-Calvé-Perthes disease, the primary cause is a transient disruption of the blood supply to the femoral capital epiphysis, followed by remodeling and the risk of loss of sphericity. The degree of perfusion impairment and the duration of remodeling determine the prognosis. [9]

Risk factors

Risk factors include intense cyclical loads in children and adolescents during the rapid growth phase, insufficient flexibility of the muscles of the anterior and posterior thighs and lower legs, as well as poor technique and a sudden increase in training volume. These factors increase the risk of pain syndromes and delay recovery. [10]

Heel pain associated with Sever's disease has been linked to a combination of internal and external factors, including changes in foot biomechanics, running volume, and footwear characteristics. Reducing impact loads and adjusting the training plan reduce the risk of recurrence. [11]

Pathogenesis

Osteochondritis dissecans represents a continuum from subchondral bone swelling to fracture and separation of the osteochondral fragment. The lesion begins in bone and then involves cartilage, which explains the differences in lesion stability and treatment approaches between skeletally immature and skeletally mature patients. [12]

Traction apophysitis is characterized by microdamage to the growth plate at the tendon insertion site, with reactive changes and pain during exercise. In the early stages, the process is reversible with load adjustment, stretching, and strengthening of the muscle groups. [13]

In Legg-Calve-Perthes disease, ischemia causes necrosis, followed by fragmentation and repair, possibly resulting in deformation of the femoral head. Maintaining the sphericity and centralization of the femoral head within the acetabulum determines the functional outcome. [14]

Symptoms

Osteochondropathies are characterized by pain associated with exertion, localized tenderness and swelling, and decreased range of motion. With osteochondritis dissecans, episodes of blockade or a feeling of joint instability are often noted, especially when localized in the knee. [15]

Osgood-Schlatter disease is characterized by anterior knee pain during running, jumping, and squatting, tenderness of the tibial tuberosity, and possible enlargement of the local bony prominence. Symptoms worsen with activity and improve with rest. [16]

In Legg-Calve-Perthes disease, limping, limited hip abduction and internal rotation, and pain after exercise are alarming. These signs require early imaging and stage stratification. [17]

Forms and stages

The main forms include osteochondritis dissecans, traction apophysitis, and epiphyseal osteonecrosis in childhood. For osteochondritis dissecans, stability classifications based on magnetic resonance imaging and arthroscopy data are used, which helps determine the choice of conservative or surgical approach. [18]

For Legg-Calvé-Perthes disease, radiographic staging and outcome classification scales are used that relate the age of onset and the extent of the lesion to the likelihood of a favorable femoral head shape at the end of remodeling. [19]

Table 1. Common osteochondropathy: age, localization, clinical accents

Nosology	Typical age	Localization	Clinical Emphasis
Osteochondritis dissecans	Teenagers, young adults	Condyles of the femur, talus, humeral capitulum	Load-bearing pain, swelling, possible joint blockages
Osgood-Schlatter disease	10-15	Tibial tuberosity	Pain when jumping and running, painful bone "bump"
Northern Disease	8-12	calcaneal tuberosity	Heel pain in runners and football players
Legg-Calve-Perthes disease	5-10	Head of the femur	Lameness, limited movement, risk of deformation
Freiberg's disease	Teenagers, mostly girls	Head of the metatarsal bone	Pain in the foot during weight bearing, swelling of the metatarsophalangeal joint

Summarized from current clinical guidelines and reviews. [20]

Complications and consequences

Without adequate management, osteochondritis dissecans can lead to the formation of loose bodies, chronic pain, decreased athletic performance, and accelerated joint degeneration. Unstable lesions and late diagnosis increase the risk of adverse outcomes. [21]

In Legg-Calvé-Perthes disease, long-term non-sphericity of the femoral head leads to acetabular incongruity and increases the risk of early osteoarthritis in adulthood. Early stratification and maintenance of centralization improve the prognosis. [22]

Diagnostics

The basic algorithm includes a clinical examination, assessment of training load, radiography in standard projections, and, if necessary, magnetic resonance imaging for staging and assessing the stability of the lesion. Computed tomography is used in complex cases to detail the bone architecture. [23]

For osteochondritis dissecans of the knee joint, the recommendations of the American Academy of Orthopaedic Surgeons of 2023 are relevant, which systematize the role of magnetic resonance imaging, observation periods and indications for surgery in skeletally immature and mature patients. [24]

Differential diagnosis

The differential diagnosis includes stress fractures, osteonecrosis of other origins, osteochondral contusions, synovial plica syndromes, tumor-like lesions of the pineal gland, as well as inflammatory arthropathies and infectious processes. Age, relationship to load, and typical imaging help narrow the range and avoid unnecessary invasive interventions. [25]

In adolescents with anterior knee pain, it is important to differentiate Osgood-Schlatter disease from patellofemoral pain syndrome and unstable osteochondral fragments. In children, transient synovitis and epiphysiolysis should be excluded, requiring targeted imaging. [26]

Treatment

General principles for stable lesions and traction apophysitis include load modification, temporary restriction of painful activities, individualized physical therapy with an emphasis on stretching the quadriceps, hamstrings, and calf muscles, as well as strengthening the muscle chains. In most cases, this leads to healing and a return to sports in growing patients. [27]

In osteochondritis dissecans, the approach depends on the age and stability of the lesion. In skeletally immature patients with stable lesions, conservative management with dynamic observation is preferred. In unstable patients or in skeletally mature patients, organ-preserving interventions with fragment fixation, stimulation of repair, or osteochondral techniques are considered according to the guidelines of the American Academy of Orthopaedic Surgeons. [28]

In Legg-Calvé-Perthes disease, the choice between observation, centralization methods, and surgical techniques depends on the age, stage, and extent of the lesion. Systematic reviews show better structural outcomes in patients younger than six and a half years with conservative management and an advantage of surgical strategies in older patients at certain stages. [29]

Table 2. Summary of treatment strategies

Scenario	First line strategy	Indications for surgery
Stable osteochondritis dissecans in the skeletally immature	Load limitation, physical therapy, monitoring	Progression, signs of instability, lack of healing
Unstable focus or mature skeleton	Preservation and fixation of the fragment, osteochondral techniques	A large unstable fragment, a failure of conservative tactics
Osgood-Schlatter disease	Activity modification, stretching and strengthening, and graded rehabilitation	Rarely, with persistent symptoms after closure of growth plates
Legg-Calve-Perthes disease	Observation and methods of maintaining centralization	Deformation, advanced age, large affected areas

Summarized from clinical guidelines and systematic reviews. [30]

Prevention

Prevention of osteochondropathy in young athletes includes sensible training planning, a gradual increase in volume and intensity, mandatory recovery days, technique correction, and regular stretching of key muscle groups. Training coaches and parents to recognize early symptoms helps reduce the incidence of chronic forms. [31]

Individualized footwear and surface recommendations, impact reduction, and timely adjustments to the training plan reduce the risk of apophysitis recurrence and accelerate return to sports. Rehabilitation programs emphasizing flexibility, strength, and balance increase resilience to recurrent pain episodes. [32]

Forecast

In most growing patients, stable lesions and traction apophysitis heal with proper management, allowing for a return to normal activity without limitations. The prognosis is worse with late diagnosis, osteochondral fragment instability, and in skeletally mature patients. This emphasizes the importance of early stratification and adherence to clinical guidelines. [33]

For Legg-Calve-Perthes disease, outcome is determined by age, stage, and success in maintaining the sphericity of the head. Appropriate management at early stages improves long-term structural and functional outcomes. [34]