Total Knee Replacement And Sports

Stresses on your new knee joint

The muscles that cross the knee joint act on the knee joint by a system of levers. The dynamic effect of these combined forces is that the resultant loads acting on the knee joint of a moving person are several times higher than the body weight.

In total knee prosthesis, the stresses are concentrated on smaller areas than in normal knees.
Here are some examples of peak loads that occur on the surfaces of a total knee joint prostheses during sport’s activities:

• bicycling produces loads of 1,2 BW (Body Weight)
• power walking produces loads of 4 times BW (Body Weight)
• hiking produces loads of 8 times BW (Body Weight)
• jogging produces loads of 9 times BW (Body Weight)

(Kuster 2000)

Moreover, the load of the joint surfaces of the total knee joint depends also on the position of the knee joint.

Load on the total knee joint surfaces

What matters is the stress on the polyethylene surface of the tibial component.

The tibial component is made of polyethylene (PE). PE has only limited resistance against high stresses. If the stresses exceed a limit, the PE will be damaged.

A – In an extended position (going on a flat ground, e.g.) the artificial joint surfaces are conforming and the contact area between them is large.

Thus, the resulting stress on the joint surface of the tibial component is low and the risk for damage of the PE plate is low too.

B – In a flexed position (going downhill, e.g.) the contact area between the joint surfaces is small. This is so because the femoral component is more curved posteriorly (back) and the joint surfaces are no longer conforming when the knee is flexed.

The resulting stress on the tibial component is high  and may even exceed the limit of the endurance of PE. The high stress on the tibial component in this position may cause damage of the tibial component .

Conclusion: don’t go downhill and when you are forced to do it, go slowly and use ski poles.

Should you participate in sports?

The question as to whether you should participate in sports after total knee replacement is up to you. The opinions on this question changed during the last ten years.

The desire to improve function and continue participation in athletic activity is very important for many patients who choose the total knee replacement.

Many surgeons today believe that patients after total knee replacement may participate in whatever activities they wish to participate after the total knee surgery if they were informed about the possible risks associated with such activity .

The surgeon should explain the risks associated with higher sport activity after the total knee replacement and about the training methods that will diminish these risks.

Ask always your surgeon and his staff to discuss with you the benefits and the risks of resuming sports after total knee surgery. The discussion should explain the risk of loosening of the total knee prosthesis, accelerated wear of the polyethylene surfaces in the knee joint, and risk of fracture of the skeleton around the total knee and other trauma.

The surgeon should explain the difference between high impact (soccer, singles tennis, jogging) and low impact sports (doubles tennis, bicycling, swimming). The risk of total knee failure, at least in theory, increases in patients performing high impact sports.
The surgeon should explain the different effect of recreational training and high volume (endurance) training on the wear of the total knee joint. The risk of total knee failure, at least in theory, increases in patients performing endurance training. (Interestingly enough, direct statistics corroborating this view are difficult to find in the medical literature.)

Patients should be also advised to postpone their sport and recreational activities until their musculature around the new knee joint is sufficiently strong to protect the new joint and prevent an unnecessary trauma.

Studies demonstrated that 49% of patients participated in sports at last one a week before the total knee surgery and 65% could participate in sport after the total knee surgery.
Only 20% of these patients returned to high impact sports, such as tennis, whereas 90% of them returned to low impact activities, such as bowling
Several studies showed that patients who resumed their athletic activity after total knee replacement experienced improved fitness of their heart and lung system.

Individual sports

Skiing: cross country skiing and downhill skiing on flat slopes loads your new total knee with about 4 times your body weight, slightly less than speedy walking. Downhill skiing on steep hills overloads your new knee with up to 8 times your body weight.
Golf: most surgeons do not discourage their patients to play golf. Studies showed that total knee patients-golfers who returned to playing golf at the mean 18 weeks after the surgery have not had higher rate of complications than the non-players. 34% of these patients noted mild to moderate pain during and after play. Golfers with left total knee replacement experienced more difficulties than did patient with right total knee replacement.
Their handicap rose with 4,6 strokes and their drive decreased an average of 12 meters. 87 % of these patients used golf cart when they played golf -highly recommended! And don’t use the spiked shoes. (Mallon 1994)
Tennis: One study showed that among the competitive tennis players with total knee replacement, only 21 % of them have had approval from their surgeon. The majority of these patients also reported that return to active tennis was the main reason for their total knee surgery. These patients played both singles and doubles tennis three times a week on average. All players were satisfied with their new knees and their ability to play tennis. Single tennis is usually considered a high impact sport which puts much load on the new hip joint. Surgeons usually do not recommend it. (Mont 2002)

Recommendations of the Knee Society

as to suitable and non-suitable sports for patients with total knee replacement are compiled in the Table. Some of the sports are recommended only to experienced patients (*).

It is important to realize that you have good chance to return to the sports you practiced already before the surgery. It is, however, very improbable that after total knee replacement you will learn and practice successfully new sports (Healy 2001)

No conclusion was reached about the following sports:

References:

• Kuster M et al. Med Sci Sports Exerc 2000;32: 721-4
• Mallon W J. South Orthop Assoc 1994;3: 295-8
• Mont M et al. Am J Sports Med 2002;30: 163-6
• Healy et al. American Journal of Sports Medicine 2001;29: 377 – 388