Injury types |
Degenerative lesions |
Articular cartilage can be damaged in joint distortion. Especially shear forces combined with compressive force can tear cartilage in a mangle like manner. That is called delamination cartilage injury. In children and young people all cartilage layers are usually torn apart from the bone. In adults, delamination injury is more often limited to the deepest calcified layers at the bottom. These layers do not have gliding properties. In practice this means that 2/3 to 3/4 of the cartilage thickness is lost, but functionally that is a 100% damage. Most accurate imaging methods like CBCT can even reveal this layer, but it's role as a functional cartilage should not be overestimated.
One of the difficult injuries for many imaging techniques are delaminated flaps which have a base. They stay on place as a hinged bonnet, and can only be seen if there is enough joint fluid between loose cartilage and bone surface. If the rupture is total, then sharp shouldered cartilage defect can be seen more easily, and in many cases detached cartilage flap can be seen as a loose body inside the joint. In either case, it can cause also mechanical symptoms. Another type of cartilage injury is a gradual degeneration after initial hit. This can most often be seen in connection to ACL injuries. Cartilage appears normal in initial imaging and during ACL reconstrution surgery, but it has got a compressive load too high to stand. Tissue degeneration starts, and consequences are seen with a couple of months delay. In these cases patient recovers well from the index procedure, knee is stable, rehabilitation proceeds well, but joint starts to react to increased exercises with swelling, stiffness and pain during the first months after initial injury. It is not exactly known what happens there inside joint and cartilage layers, but cartilage is destroyed very fast. At the moment we do not have knowledge enough to say if something protective could be done after this kind of injuries. |
Diagnostics of osteoarthrosis (OA) degree is very much based on old Kelgren-Lawrence classification. It includes notable changes in the joint space width (JSW) in early osteoarthrosis, followed by subchondral bone plate thickening, osteophyte formation and bone cysts formation. This is a widely available way to describe OA degree, but it is also very simplified model of OA. It is now known, that osteoarthrosis is a multifactorial disease of the whole joint. Cartilage thinning can be partly reason, but also a consequence of other processes in joint. These processes remain to be understood in coming years, but currently late phase OA findings are mostly seen as an indication to even total joint replacement if the patient has OA symptoms.
One of the biggest questions in cartilage related problems is if we can distinguish between traumatic cartilage lesions and degenerative cartilage thinning. It is not easy, but there is now increasing data that modern imaging methods can give answers to this in the near future. Increasing spatial resolution with cone beam CT (CBCT) scanner and contrast media reveals cartilage layers with ultra high 0.2 resolution in any given direction. This offers a novel insight to cartilage layers in clinical work. Another way is to combine physiological parameters to different imaging methods, giving some information on functional condition of cartilage like in dGEMRIC MRI, or penetration of contrast media inside cartilage in delayed CT scans. Subchondral bone plate is a crucial player in OA. It's mineral density would be of interest, and it has been measured in a clinical setting. It seems to correlate to ICRS OA grading, but much further work is needed on that area. |
|
The content of this website is provided for information only and is not intended to be used for diagnosis or treatment or as a substitute for consultation with your own doctor or a specialist.Email addresses supplied are provided for basic enquiries and should not be used for urgent or emergency requests, treatment of any knee injuries or conditions or to transmit confidential or medical information.
|