In exceptional cases, injury to the extensor apparatus can occurduring the implantation of artificial knee joints. This is a rare but serious complication following total knee arthroplasty (knee TEP) surgery.
You can find out which injuries to the extensor apparatus are possible after a knee replacement and how treatment is carried out here.
Damage to the extensor apparatus can occur during the surgical implantation of a knee TEP.
Excessive strain or uncontrolled, jerky mobilization after an operation can lead to injuries to the extensor apparatus. The patellar ligament is typically affected.
Late loosening of the implant or misplacement of the joint inlay can also lead to tissue damage to the extensor apparatus.
This must be distinguished from restrictions in the function of the extensor apparatus without mechanical tearing of the structures.
These include bleeding and bruising of the thigh muscles following a tourniquet or neurological microtraumatization in the thigh area.
A reflexive or psychogenic reduction in active extensibility is also possible in the event of temporary postoperative functional disorders.
Depending on the surgical approach, these can be assessed as physiological adaptation in the early phase. However, they can also persist over a prolonged period as part of adaptation disorders.
Knee TEP in X-ray image © LittleSteven65 / Fotolia
Complete extension of the knee, in particular active extension against the force of gravity of the horizontally extended leg, is not possible
Pain in the knee area, especially when trying to actively extend the knee against resistance. Rarely also during the stabilization phase when walking.
Change in gait or limping to relieve the affected leg.
Tendency to fall due to lack of muscular stabilization of the leg at the start of flexion.
Muscle atrophy and thus further loss of strength in the quadriceps muscle
Conservative therapeutic measures have no prospect of success in the event of complete loss of the extensor apparatus.
In order to avoid surgery, orthopaedic functional orthoses (externally applied splints) can partially restore everyday function in various forms.
However, the everyday comfort of these splints is not satisfactory for patients, which is why they are not widely used.
If the extensor apparatus is partially dysfunctional, targeted exercises can help to improve function.
Electrical stimulation can help to activate a weakened quadriceps muscle and improve function if the anatomical structures are intact.
Electrical stimulation can be used to strengthen weak muscles after knee surgery@ neotemlpars106 /AdobeStock
If the quadriceps tendon is torn, doctors can suture it surgically to restore function.
In severe cases, transplantation of tendons or muscles from other parts of the body is an option to restore function. The use of artificial tendon replacement tissue is also possible.
If loosening or misplacement of the implants is the cause of the injury, a new operation on the prosthesis is necessary.
If it is not possible to surgically restore the extensor apparatus, the affected knee joint is stiffened. However, the ability to bend the knee is reduced.
The choice of treatment option depends on
Accurate diagnosis and appropriate treatment are crucial to restore the function of the extensor apparatus after a knee TEP.
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