A group of conditions in which there is compression, fragmentation or separation of a small segment of articular cartilage and bone. The affected area show the features of ischemic necrosis include death of bone cells in the osteoarticular fragment and reactive vascularity and osteogenesis in the surrounding bone. The disorder occur mainly in adolescence and young adult during phase of physical activity and initiated by trauma or repetitive stress. Some children are unusually predisposed to bone ischemia because of an underlying vascular coagulopaty. Pathology: Impact injury may cause bleeding or edema in the subarticular bone result in capillary compression or thrombosis and localized ischemia. Osteo articular fracture cause severance of local blood supply and separation of a necrotic osteo chodral fragment.

Traction injury similarly damage the blood supply to an apophysis. Crushing osteo chondritis: Occur in late adolescence but adult also affected. Characterized by spontaneous necrosis of ossific nucleus in a long bone epiphysis or one of the cuboidal bone of the wrist or foot. Local anatomical feature as metatarsal bone longer than usual or disproportion in length of radius and ulna result in undue compression stress being applied to bone. Pathological changes : bone death, fragmentation or distortion of the necrotic segment and reactive new bone formation around the ischemic trabiculea. Clinical feature: pain and limitation of joint movement, tenderness is sharply localized to the affected bone. X- ray: show increase density and in later stages there is distortion and collapse of necrotic segment. Common example: Freiberg disease of the metatarsal, Kohler disease of the navicular, Kienbock disease of the carpal lunate and Panner disease of capitulum, Scheuermann disease of the vertebral end plate.

Splitting osteo chondritis: Small segment of articular cartilage and subjacent bone separate “dissect” as a vascular fragment. Typically occur in young adult usually men. Affect particular site: the lateral surface of the medial femoral condyl in in the knee, the antero medial corner of the talus in the ankle, the superomedial part of the head of the femur in the hip joint, the humeral capitulum, and first metatarsal head. The cause: repeated minor trauma result in osteo chondral fracture of the convex surface and fragment lose it’s blood supply. Clinical feature: the knee is most commonly affected and patient present with intermittent pain, swelling and joint effusion, if the affected fragment become completely detached it may cause locking of the joint or the giving way. X-ray: in tangential projection, the dissecting fragment is defined by radiolucent line of demarcation, when separate the resulting crater is obvious. MRI: show early changes before x-ray as decrease signal intensity in the area around the affected osteo chondral segment. Radionuclide scan by Tc-HDP show marked increase activity in the same area.

Treatment: early; load reduction and restriction of activity in children this cause complete healing while in adult the future coarse is doubtful. later; partially detached fragment pinned back in position after roughening of the base, while completely detached fragment; pinned back if large and preserved, or else completely removed. Pulling osteochondritis: traction apophysitis Result from tensile stress of physeal junction cause localized pain and increase radiographic density in the unfused apophysis. Seen at tibial tuberosity “Osgood Schlatter disease” and the calcaneal apophysis “Sever disease” both subject to unusual traction force from powerful tendon which insert in to the apophysis. Kienbock disease: Relative shortening of the ulna “ negative ulnar variance “ predispose to chronic stress over load of the lunate between the distal edge of the radius and the carpus cause ischemic necrosis “ traumatic softening of the lunate”.

Pathology: Stage I: ischemia without necked eye or radiographic abnormality. Stage II: trabicular necrosis with reactive new bone formation and increase radiographic density but little or no distortion of shape. Stage III: collapse of bone. Stage IV: disruption of radio carpal congruence and secondary OA. Clinical feature: patient young adult complain of pain and stiffness, tenderness is localized over the lunate & grip strength is diminished, in later stages wrist movement is limited & painful. X-ray: in stage I; show no abnormality but radio scintigraphy reveal increase activity & MRI most reliable in detecting early changes. In stage II; x-ray show mottled or diffuse density of bone, in stage III; the bone lock squashed & irregular & in stage IV; there are OA changes in the wrist. Treatment: A) non operative; splinting of the wrist for 6-12 weeks relief pain & possibly reduce mechanical stress. B) operative; 1- if pain persist, 2- bone begin to flatten; while the wrist architecture is only minimally disturbed up to stage III the aim is to reduce carpal stress by shortening of the radius or lengthening of the ulna.

If the bone become collapsed ;1- lunate replacement by prosthesis. 2- inter carpal fusion. 3- excision of the proximal raw of carpus. C) If pain & restriction of movement become sever radio carpal arethrodesis give stable pain free wrist. Osgood Schlatter disease: apophysitis of tibial tubercle Traction injury of the apophysis in to which part of the patellar tendon is inserted cause painful swelling of the tibial tubercle occur commonly in adolescence. There is no history of injury & some time the condition is bilateral. A young adolescent complain of pain after activity & of tender lump, it’s situation over the tibial tuberosity is diagnostic some time active extension of the knee against resistance is painful. X-ray: reveal fragmentation of the apophysis. Treatment: spontaneous recovery is usual but take time & it is wise to restrict activity as cycling & soccer. If symptoms persist even after wearing back splint there may be separate ossicle in the tendon which need removal.