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OTHER
COMPLICATIONS of TOTAL KNEE SURGERY
CONTENTS:
Loosening
Instability
Fractures around total knee
Patellar problems
Patellar clunk syndrome
Increasing rigidity of the
total knee
Swollen total knee joint
Component breakage
Injury of the peroneal
nerve
Pain in the scar
Damage of the vessels
There is a host of other possible complications that may
occur after total knee surgery, many of them taking place with exceeding rarity. The
discussion of these complications is not intended to scare you. If I discuss these
complications, it is for the benefit of the very occasional patient who unfortunately
experienced such a complication and needs more information about it.
1
Loosening
of the components is the most common cause of failure of
all types of total knee prostheses. Most often loosens the tibial component, followed by
patellar component and femoral component. The loosening is a continuous process causing
increasing discomfort.
The loosening rate of total knee prostheses is about one
percent per year. That means that after 10 years 10 % of all patients with a total knee
joint will have their total knee prostheses failed by loosening and exchanged.
If the patient experiences increasing pain and
stiffness in the loose total knee, the surgeon usually recommends revision operation. The
discussion is still ongoing whether it suffices witch exchange of the loose component
only, or whether the whole total knee prosthesis should be exchanged.
(See also the chapter Loosening of total joints)
2
Instability of the total knee joint
has occurred in between 1 to 6 % of all total knee joints.
Patient may just feel that the knee totters a little, in severe case of instability the
patient just doesn’t dare to put weight on the unstable knee.
Uncorrected major knee joint instability will put excessive
stress on total knee components and will eventually cause prosthetic loosening and
destruction of the whole total knee prosthesis.
In most instances treatment is by use of walking aids,
simple knee braces, and more extensive ankle -knee braces (orthosis). Surgical tightening
of the soft tissues around the prosthesis have usually not been effective in stabilizing
the total knee.
An alternative operation is to exchange the polyethylene
liner - put a higher liner in. This will tighten the slack soft tissues
If the instability is severe, the surgeon has the option
remove the old unstable total knee prosthesis and put in a more constrained model of the
total knee prosthesis. ( see the chapter Linked total knee)
3
Fractures around the total knee prosthesis
Such fractures usually occur after relatively minor
injuries. Patients with "softer" bones, such as patients with rheumatoid
arthritis, are at greater risk for these fractures. More commonly these fractures occur in
the femoral shaft at the tip of the stem of the femoral component.The patient feels pain
above the fracture site and the X-ray pictures then show the fracture.
Statistics show that these fractures occur in about 0,1% of
all total knee prostheses (Furnes 2002) . The majority of these fractures can be managed
by braces, only displaced fractures need operative treatment.
4
Patellar problems
Patellar problems comprise the largest number of
complications after total knee replacement and have been reported in from 6 to 30 % of all
total knee replacements.
The patient with patellar problems has pain in front
of his / her new total knee.
In a total knee joint where the surgeon did not replace the
patella, the anterior knee pain not seldom leads to additional operation with
replacement of the patellar joint surface. But this additional replacement of patella does
not always stop the pain
In a total knee joint where the surgeon replaced the
patella already at the first operation, the patient may feel pain, clunking and
instability of the replaced patella.
The cause of the pain is the fact that no total knee
prosthesis model can imitate the complicated track that the patella follows during the
extension and flexion of the normal knee joint.
All models of total knee prostheses force the patella to
follow a straight track during the knee movement, which leads to increased wear of the
patella and faulty tension in the soft tissue that keep the patella in the right track.
This mechanical mismatch causes subluxation , dislocation,
and fracture of the patella, loosening of the patellar component, damage of the patellar
component, and pain of uncertain origin.
The treatment of patellar problems in a total knee is
difficult.
For an unstable patella, the surgeon may try to balance the
soft tissues around the patella. Most often such an operation implies making cuts in the
soft tissues that force the patella back on the right track.
Destructed patellar components must be exchanged.
5
Patellar clunk syndrome
Some patients feel a painful clunk in front of their total
knees when they bend the knee between 30 and 45 degrees. Sometimes the patient cannot move
the knee beyond this range.
The cause is a soft tissue lump that forms on the joint
capsule just above the patella. At 30 - 45 degrees of flexion, the lump catches the
anterior flange of the femoral component, causes pain, and blocks further movement.
The treatment is by removal of the lump. It may be done by
arthroscopic (key hole) surgery.
6
Increasing rigidity of the total knee joint
If, in about two weeks, you will not achieve 90 degrees of
flexion in your new knee, your surgeon might suspect that scar tissue has formed in your
knee and hinders the movement. The surgeon might recommend a manipulation of your new knee
joint in narcosis. You would be put to sleep and the surgeon will passively bend your knee
to 90 degrees or more if possible. This forcible bending should break down the scar tissue
that has been forming in your new knee.
The manipulation must be done carefully because there is
always risk of a skeletal fracture.
Statistics show that at risk are patients with second
operation in their knees and patients with diabetes.
7
Swollen total knee joint
Transient swelling of the total knee joint after too much
activity is not uncommon. It will disappear without specific treatment.
Lasting swelling of the total knee joint together with pain
may by a sign of
increased wear of the polyethylene components
infection of the total knee joint.
The surgeon usually takes a sample of the joint fluid
for bacteriological examination. This is done by a puncture of the joint with a fine
needle; with proper technique the puncture should not be painful.
The treatment then depends on the condition that produced
the swelling.
The damaged polyethylene components must be exchanged
The infection must be treated accordingly (see the
chapter Wound infection)
8
Component breakage
occurs as breakage of polyethylene components, mainly
tibial, in about 0,1 % of all total knees. It is due by the
excessive pressure put on these components. Breakage of metallic components of the
total knee prosthesis is exceedingly rare nowadays.
The signs are pain, stiffness, and often also swelling of
the total knee. Special X-ray pictures may disclose the damage.
The treatment is by exchange of the damaged components. At
operation, the surgeon may discover that the damage is more widespread then suspected
before the revision operation and whole total knee joint must be exchanged.
9
Injury of the peroneal nerve
is reported in 0,3% to 4% of all total knee operations
(Idusuyi 1996)
The patient feels tingling and numbness in the foot, in
cases of more serious damage the patient cannot stretch the foot. These symptoms are
caused by the damage of the peroneal nerve. If you notice these symptoms notice
immediately your doctor.
The peroneal nerve crosses the knee joint on the outside.
It lies there directly beneath the skin on the hard fibula bone (lesser shin bone) and can
be damaged by direct pressure from outside by tight splints and dressings.
It is important that the knee after the operation is NOT
rotated outward, lying on a brace or continuously moving machine.
It is important that there is no unpolstered rail in the
brace or bed, coming in contact with the knee joint.
It is important that the patient who has a continuous
postoperative pain relieving drop or epidural anesthesia is followed closely. These
patients have impaired sensation, and cannot feel the pressure and numbness in the leg
properly.
It is also suspected that correction of the
contracture of the knee joint during the total knee replacement may stretch the nerve too
much and damage it.
Patients with rheumatoid arthritis are at higher risk to
experience peroneal nerve damage after THR than other patients (Schinsky 2001)
If there is suspicion of nerve damage, all postoperative
dressings must be immedialy cut and removed. The wound must be inspected to exclude
accumulating blood pool (haematoma) that may exert pressure on the nerve.
In most cases all symptoms disappear after proper
treatment. The patient is usually fitted with a protective brace, loose dressings
are applied, the knee is slightly bent and physiotherapy is started. Some surgeons
do also EMG evaluation of the muscles innervated by the peroneus nerve, other surgeons use
the EMG examination only to follow the improvement.
Surgical revision of the nerve is rarely needed.
10
Pain in the scar
is not so rare. The pain occurs either spontaneously or
when the patient touches the scar. Some patients feel a sensation of small
"electrical shock" when touching the scar.
This phenomena is caused by damage to small branches of the
main skin nerve (with the name nervus saphenus). The nerve lies on the inside of the knee
and its branches cross the middle line of the knee. The cut through skin in midline
damages some of these branches. Sometime the scar tissue around these branches then causes
pain or "electricity shocks" when touching them. In most cases this
condition needs no treatment.
11
Damage of the vessels around the
knee
is very rare. At risk are patients with known vascular
disease and patients with previous operation on the knee.
The symptoms are intensive pain in a cold, pale, pulse-
less leg. This situation demands an acute consult with the vascular surgeon to decide on
further action.
References:
Furnes et al.: Acta Orthop Scand 2002; 117-29
Idusuyi O et al.: J Bone Joint Surg-Am,
1996;78-A: 177- 84
Schinsky et al.: J Arthroplasty 2001;16: 1048-54
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