The patello-femoral joint
Mal-tracking, lateral release, medial reefing, tibial tuberosity transfer, patellar arthritis, patellectomy, plica, patello-femoral braces. For patellar fractures, see Board on 'Bone Breaks around the knee'.

Ruptured patellar tendon or ruptured quadriceps tendon
Rupture of one of the major tendons attaching to the top or the bottom of the patella.

Rotational deformities of the leg
Tibial rotational deformity, femoral rotational deformity, miserable malalignment, hip rotations

Bone breaks around the knee
Tibial plateau fractures, femoral fractures, fractured patella

Osgood Schlatter's Disorder
Chronic inflammation of the lump below the kneecap.

Overuse problems of the knee (except Osgood Schlatter's)
Jumpers knee, iliotibial friction band syndrome, tendinitis, bursitis, muscle strains and sprains

Loose bodies
Bits of loose joint cartilage or torn meniscus floating in the joint, and causing painful catching.

Meniscus
Tears, trimming, meniscectomy, meniscal repair, meniscal transplant, synthetic menisci, meniscal cyst

Rheumatoid Arthritis (and its variants)
Rheumatoid arthritis, juvenile rheumatoid arthritis, Still's disease - types of arthritis where usually many joints are affected and patients are often quite ill.

Joint hypermobility disorders
Over-lax joints, Ehlers Danlos Syndrome, etc

Imaging (MRI, X-rays, CT etc) and other investigations.
General discussion issues about tools used for making a diagnosis. Also retrieving notes and reports.