Patella dislocation

Description:

Dislocations of a patella make 0,4-0,7% of total quantity of dislocations. The probability of dislocation of a patella increases at a small patellar hollow, poorly developed outside condyle of a hip, disturbance of ratios between an axis the four-head of a muscle and own ligaments of a patella. Usually until an injury these anatomic features are not shown and remain unnoticed in any way.

Patella dislocation reasons:

The probability of dislocation of a patella increases at a small patellar hollow, poorly developed outside condyle of a hip, disturbance of ratios between an axis the four-head of a muscle and own ligaments of a patella. Usually until an injury these anatomic features are not shown and remain unnoticed in any way.
As a rule, the direct injury (falling on a knee joint, side blow to the area of a patella) which is combined with reduction by the four-head of a muscle becomes the reason of dislocation of a patella. Side dislocation of a patella usually arises at the unbent shin. When bending in a knee joint side dislocation is almost impossible as the kneecap is densely pressed to the intercondyloid surface of a femur. In rare instances at the bent shin vertical dislocation of a patella is possible.

Classification:

In traumatology distinguish the acquired (traumatic) and congenital dislocations of a patella.

Depending on prescription of an injury allocate acute and chronic dislocation of a patella. If dislocation occurs repeatedly, speak about habitual dislocation.

In the direction of shift distinguish:
side dislocations of a patella (outside and internal);
the torsion (rotational) dislocations at which the patella is developed around the vertical axis;
vertical dislocations at which the patella is developed around the horizontal axis and puts in a joint crack between tibial and femoral bones.

Outside is most often observed, is more rare – internal dislocation of a patella. The torsion and vertical dislocations of a patella meet extremely seldom.

Patella dislocation symptoms:

Acute traumatic dislocation of a patella is followed by sharp pain. The knee joint is slightly bent, increased in volume, is expanded in the cross direction (at side dislocations). The active movements are impossible, passive are painful and sharply limited.

Palpatorno is defined the direction and degree of shift of a patella. At a complete dislocation the patella is located knaruzh from a hip ectocondyle, at incomplete – is over an ectocondyle.

Sometimes traumatic dislocation of a patella is set independently. Patients in such cases note an episode of a sharp scelalgia which was followed by feeling of a podkashivaniye and shift in a knee. After independently set dislocation of a patella insignificant or moderate hypostasis in the field of a knee joint is observed. The hemarthrosis is possible (accumulation of blood in a knee joint).

Diagnosis:

The diagnosis of dislocation of a patella is exposed by the traumatologist on the basis of the characteristic anamnesis, a clinical picture and data of a X-ray analysis. The comparative roentgenograms of both patellas which are carried out at the tangent direction of X-ray in front and from top to down or from below up are most informative.

The basis for diagnosing of habitual dislocation are the repeated shifts of a patella occurring without the expressed traumatic influence. Habitual and chronic dislocations of a patella can be the indication for carrying out MRT of a knee joint. At the solution of a question of expediency of operation the diagnostic arthroscopy of a knee joint is carried out.

Treatment of dislocation of a patella:

Acute dislocation of a patella is usually treated conservatively. Make reposition of dislocation under local anesthesia. The extremity is bent in a hip joint (for weakening of a tension of sinews by the four-head of a muscle) and unbent in a knee joint. Then accurately displace a patella before elimination of dislocation and apply a plaster bandage.

After reposition surely appoint the control roentgenogram for confirmation of reposition of dislocation and identification of osteoarticular bodies which are sometimes formed at an injury.

At acute dislocation of a patella the immobilization of 4-6 weeks is shown. Massage and physiotreatment carry out under control of the physiotherapist, without removing a splint. Full load of a leg is resolved in a month from the moment of an injury.

Operational treatment of acute dislocation of a patella is carried out at identification of osteoarticular bodies and the high probability of repeated dislocations caused by changes in a knee joint.
Old and habitual dislocations of a patella are the indication to operational treatment. After operation the immobilization for a period of 4 — 6 weeks is shown. The full volume of movements in a knee joint is allowed in 8-10 weeks.