Chronic discharging sinus with bone particle is seen in
Clinical features of chronic osteomyelitis 

The commonest presenng symptom is a chronic discharging sinus, a history of bone piece discharge from the chronic sinus is considered diagnosc of chronic osteomyelis.
Pain is minimal or absent.
Generalized symptoms of acute osteomyelis are not present except in acute excacerbaons.
On examinaon there is irregular thickening of bone. Mild tenderness may be seen in deep palpaon. Adjacent joint may be sff.

Radiological features
Following are radiological features : -

Thickening and irregularity of the corces.
Patchy sclerosis
Bone cavity : This is seen as an area of rarefacon surrounded by sclerosis.
Sequestrum(Manipal 97): This appears denser than the surrounding normal bone because the decalcificaon which occurs in normal bone, does not occur in dead bone. Granulaon ssue surrounding the sequestrum gives rise to a radiolucent zone around it. A sequestrum may be visible in so ssue.
Involucrum and cloacae may be visible
Chronic osteomyelitis
Acute osteomyelitis
Subacute osteomyelitis
Garre’s osteomyelitis