Or it will develop into a pseudarthrosis between condylar bone core and osteochondritis flake leaving the articular cartilage it supports prone to damage.

During an immobilization period, isotonic exercises, such as straight leg raises, are commonly used to restore muscle loss without disturbing the cartilage of the affected joint.

Once the immobilization period has ended, physical therapy involves continuous passive motion (CPM) and/or low impact activities, such as walking or swimming.

Many other conditions were once confused with OCD when attempting to describe how the disease affected the joint, including osteochondral fracture, osteonecrosis, accessory ossification center, osteochondrosis, and hereditary epiphyseal dysplasia.

The disease progresses rapidly beyond stage II, as OCD lesions quickly move from stable cysts or fissures to unstable fragments.

Just as OCD shares symptoms with common maladies, acute osteochondral fracture has a similar presentation with tenderness in the affected joint, but is usually associated with a fatty hemarthrosis.

Although there is no significant pathologic gait or characteristic alignment abnormality associated with OCD, the patient may walk with the involved leg externally rotated in an attempt to avoid tibial spine impingement on the lateral aspect of the medial condyle of the femur.

[18] The incidence of repetitive strain injury in young athletes is on the rise and accounts for a significant number of visits to primary care;[19] this reinforces the theory that OCD may be associated with increased participation in sports and subsequent trauma.

[19][20] High-impact sports such as gymnastics, soccer, basketball, lacrosse, football, tennis, squash, baseball and weight lifting may put participants at a higher risk of OCD in stressed joints (knees, ankles and elbows).

With disruption of the epiphyseal plate vessels, varying degrees and depth of necrosis occur, resulting in a cessation of growth to both osteocytes and chondrocytes.

These include revascularization and formation of granulation (scar) tissue, absorption of necrotic fragments, intertrabecular osteoid deposition, and remodeling of new bone.

In OCD of the knee, people may walk with the involved leg externally rotated in an attempt to avoid tibial spine impingement on the lateral aspect of the medial condyle of the femur.

In older people, the lesion typically appears as an area of osteosclerotic bone with a radiolucent line between the osteochondral defect and the epiphysis.

Treatment options include modified activity with or without weight bearing; immobilization; cryotherapy; anti-inflammatory medication; drilling of subchondral bone; microfracture; removal or reattachment of loose bodies; mosaicplasty and osteoarticular transfer system (OATS) procedures.

[47] As a result, surgery is often required in even moderate cases where the osteochondral fragment has not detached from the bone (Anderson Stage II, III).

[48] Candidates for non-operative treatment are limited to skeletally immature teenagers with a relatively small, intact lesion and the absence of loose bodies.

The goal of non-operative intervention is to promote healing in the subchondral bone and prevent potential chondral collapse, subsequent fracture, and crater formation.

[51] Consequently, the type and extent of surgery necessary varies based on patient age, severity of the lesion, and personal bias of the treating surgeon—entailing an exhaustive list of suggested treatments.

While small lesions can be resurfaced using this form of surgery, the repair tissue tends to have less strength than normal hyaline cartilage and must be protected for 6 to 12 months.

[57] In attempts to address the weaker structure of the reparative fibrocartilage, new techniques have been designed to fill the defect with tissue that more closely simulates normal hyaline articular cartilage.

ACI surgery has reported good to excellent results for reduced swelling, pain and locking in clinical follow-up examinations.

[60] Similar to OATS, arthroscopic articular cartilage paste grafting is a surgical procedure offering cost-effective, long-lasting results for stage IV lesions.

A bone and cartilage paste derived from crushed plugs of the non-weight-bearing intercondylar notch can achieve pain relief, repair damaged tissue, and restore function.

Although each case is unique and treatment is chosen on an individual basis, ACI is generally performed on large defects in skeletally mature people.

Continuous passive motion (CPM) has been used to improve healing of the articular surface during the postoperative period for people with full-thickness lesions.

[64] A rehabilitation program often involves protection of the compromised articular surface and underlying subchondral bone combined with maintenance of strength and range of motion.

A six to eight-week home or formal physical therapy program is usually instituted once the immobilization period has ended, incorporating range of motion, stretching, progressive strengthening, and functional or sport-specific training.

[48] The prognosis after different treatments varies and is based on several factors that include the age of the patient, the affected joint, the stage of the lesion and, most importantly, the state of the growth plate.

Open growth plates are characterized by increased numbers of undifferentiated chondrocytes (stem cells), which are precursors to both bone and cartilaginous tissue.

[81] In 1870, James Paget described the disease process for the first time, but it was not until 1887 that Franz König published a paper on the cause of loose bodies in the joint.