Cause
During embryonic and fetal development in the womb, the kneecap is first cartilaginous and then, as it grows, undergoes bony transformation starting from one point (ossification). In some cases, this ossification process can start from several so-called bone nuclei, whereby the individual bony structures then fuse over time, so that a uniform bone surface is usually formed. Previous assumptions have been that in the patella bipartita, this fusion of the bone nuclei does not occur and that the individual sites do not become fully fused. Nowadays, however, it is more likely that ossification of a cartilaginous plant occurs in an area where a bone dent is also formed (emargination).
Therapy
Treatment of the patella bipartita is only necessary if it is accompanied by restrictive symptoms. If this is not the case, it is usually left untreated, as it does not indicate any disease value. If the pain is load-dependent, painkillers and anti-inflammatory drugs (e.g. ibuprofen or diclofenac) can be used for a short time.In exceptional cases that are refractory to therapy, surgical treatment of the two-part patella can also be considered, whereby the unconnected bone fragment is usually removed or – in the case of a two-part fracture with larger portions – the same procedure is used as for the treatment of a fresh patella fracture: The means of choice is the use of Kirschner wires in the course of performing a tension cord osteosynthesis (the two bone portions are brought together by means of the wires; the tensile force acting on the wires is converted into compressive forces).
Patella bipartita rarely requires treatment because it usually does not cause any symptoms. However, if it does cause pain and conservative treatment with painkillers and anti-inflammatory agents has been exhausted, surgery can help. In most cases, a knee endoscopy (arthroscopy) is recommended first for knee rehabilitation.
In order to remove the painful patella fragment, a small incision is made at the side of the kneecap in the course of the tendon of the vastus medialis muscle. Now the unconnected and painful fragment can be removed. Alternatively, the fragments could also be connected with wires as part of the tension belt osteosynthesis, similar to the procedure used in the case of a fracture of the patella.
After the operation, the knee is usually fitted with a knee orthosis for 10-14 days, but full weight bearing is still possible. The knee should also be loaded immediately, if necessary physiotherapy can help in the healing process. Sport can be resumed after about 4 weeks.
Physiotherapy can be a good help with knee problems. Through specific exercises and strengthening of the muscles of the thigh, complaints caused by a patella bipartita can be reduced. However, a complete cure cannot be achieved through physiotherapy.
If complaints persist despite muscle strengthening and painkillers, surgical removal of the patella fragment is the therapy of choice. However, physiotherapy is also a great help in the recovery after surgery.
