Patella (Knee Cap) Dislocation Requires Urgent Treatment
Longterm effects of patella dislocation
Each episode of patella dislocation can cause irreparable damage to the cartilage surface of the patella. In many cases the dislocation results in osteochondral shear fractures. Loose bone or cartilage fragments may lock the joint, which may lead to further cartilage damage at other parts of the joint. There is also the risk of tearing the intra-articular ligaments of the articular capsule.
Kneecap dislocation can cause recurrent patellar instability
After an initial acute kneecap dislocation, about 50% of patients develop recurrent patellar instability if treatment is not managed properly. The probability of retropatellar chondral damage or a patellar chondropathy increases considerably with each dislocation. For this reason the treatment aim is to stabilise the kneecap and avoid further patella subluxations, to provide pain relief and, in the long term, to avoid arthritis developing in the knee joint.
After patella subluxation osteochondral fragments are reattached
After a first subluxation without further risk factors, patients usually undergo non-surgical treatment such as physical therapy. However if there are risk factors which may cause further dislocation or recurrent dislocation, surgery may be required. In the case of a shear fracture (a detached osteochondral fragment) the main priority is to reattach the fragment. If this is not possible, the fragment should be removed, in order to prevent further cartilage damage.
Surgical reconstruction of knee cap position by suture
If there is an isolated tear of the proximal intra-articular ligaments of the kneecap without the presence of further risk factors, the suture and plication of the tissue concerned (use of a medial double-plating technique) are necessary.
Surgical reconstruction of knee cap position by autogenic tendon grafts
There are different surgical reconstruction techniques, but all make use of an autogenic tendon graft, in most cases a semitendinosus graft. Usually the tendon is attached to the kneecap via a borehole to the femur, by means of a resorbable screw, or onto the adductor magnus tendon without a screw. Results for all methods are good, but if extensive cartilage lesions are present, this may have a negative influence on the outcome of the operation.