The lives of some elderly people are rendered miserable by progressive bow-leg deformity brought on by arthritic destruction of both knee joints.

Total knee replacement offers a chance for a return to a near normal life, but can be demanding on the surgeon when the condition has been allowed to progress to extremes.

 

bow legs

This 78 year old lady had suffered for many years from destructive arthritis of both knees, leading to a great deal of pain and instability . Eventually crippling varus deformity (bow legs) severely hindered her mobility and made simple tasks like dressing extremely difficult. Struggling to walk was now also causing pain in her back.

 

arthritisarthritis

X-rays of both knees showed bilateral severe tricompartmental osteoarthritis ( joint damage of all bony contact surfaces in the knee).

Gross tibial (shinbone) defects were noted, mainly over the posterior medial aspect of the tibial plateau .

There was thinning of the bone stock (osteoporosis and cysts), disruption of the mechanical axis and many osteophytes (irregular bony outgrowths).

 

Issues

A total knee replacement would offer her almost complete correction of her disability , but the arthritis had been left until there was insufficient quality bone to hold the prosthesis (metal/plastic implant).

Also both knees would need to be done at the same time - otherwise the operated leg would be longer than the other, making her life even more difficult.

Balancing was critical in this case, as one had to ensure an accurate cut of the tibia and then referencing off from the tibia before cutting the femur . This was to ensure that sufficient external rotation of the femur was done.

The patellae would also need to be resurfaced.

 

building up the tibial plateauarthritic knee

Surgery confirmed the severe damage inside the joint. This femur should be covered with shiny white joint cartilage .

The tibial defects were built up using autograft (the left over bone) from the cut sections of the distal femur and tibia and fashioned to ensure as good a press fit as possible and then held together with wires and screws.

 

 

bow legs correctedknee replacement

With the knee replacement in place, the mechanical axis was fully restored. You can see the screws holding in place the extra bit of bone that was added.

The patient was able to return to a normal lifestyle. This case illustrates the difficulties when arthritis is neglected until there is severe varus deformity and the bone is in a really bad state.

 

 

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