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Surgical planning

Surgical planning in orthopaedics is a multi-step process. It means preparation for a planned surgery. Planning is different for each type of operation, and is sometimes overlooked in emergencies. However, this is an important step to allow acceleration of treatment and to increase its effectiveness.

The first step in planning is diagnosis, assessment of disease and orthopaedic examination evaluating range of joint motion, stability, etc.

Medical imaging techniques

The next step is to take diagnostic images, which, depending on a disease, can be for example:

  • single X-ray image - organs override each other on image, bones are visible as the brightest areas,
  • series of the CT sections - patient receives a higher dose of X-rays than in the X-ray, however, organs does not override each other,
  • series of the MRI sections - patient does not get X-rays, but bones are less distinguishable - not seen as the brightest areas of pictures.
Pelvis imaged with the X-ray

Pelvis imaged with the X-ray

Hip joint imaged with the CT

Hip joint imaged with the CT

Arm imaged with the MRI

Arm imaged with the MRI

Each of these methods allows for non-invasive imaging of man's interior. They differ in imaging efficiency of various tissues and in the amount of produced harmful radiation. Therefore, physician must assess on the basis of an interview which method will allow him to assess patient's diseased body parts and to minimize the radiation dose. The most commonly used in orthopaedics method is the X-ray, the CT less often. They are most often used to assess traumatised and pathologically changed joints. These structures are very well indicated by X-ray images, as bone strongly weakens X-rays, in contrast to other tissues. Thanks to that on these images bones are seen as very bright spots on a gray background of soft tissues.

With appropriate X-rays or CT series, we can proceed to the next step. Procedure using series of sections runs differently from using X-rays.

Procedure planning with X-rays

Screenshot from Planner 2D application used to prostheses fitting and surgery planning

Screenshot from Planner 2D application used to prostheses fitting and surgery planning

Using a single radiograph and special software (eg. Planner 2D) allows for precise measurements of joint or bone, such as diameter of head or acetabulum, limb length discrepancy, designation of joint mechanical axis. All of these measurements allow doctors to assess the extent of pathological condition, and to select appropriate treatment techniques.

Full arthroplasty

One example of hip joint dysfunctions treatment is full arthroplasty. It involves total joint replacement by prosthesis, wherein the components are:

  • stem - usually titanium or steel,
  • head - steel, titanium or ceramics,
  • articular socket - ceramics or polyethylene.

Each patient is different and, unfortunately, experience and first glance do not allow for accurate selection of such a set of implants that best fits into a case. But there are programs that make it possible to adjust implants based on X-rays. Measuring or defining bone channel axis instruments allow to choose the best size and position of implant. In case of uneven limbs, even to visualize the final result of an operation.

3D modelling

Screenshot from Bone Extractor application used to 3D modelling and surgery planning

Screenshot from Bone Extractor application used to 3D modelling and surgery planning

Tomographic series gives doctor other possible extension of his knowledge about a case of disease through 3D modeling. With such data and appropriate software (eg. Bone Extractor) doctor is able to visualize three-dimensional structure of patient's body. Well prepared model enables virtual pathology analysis. Furthermore, some programs offer model export into a format that can be 3D printed. This means that doctor is able to perform analysis on a material model of body part. In the case of orthopaedics it is bone tissue.

Disposable tools design

3D print of bone model with 3D printed disposable drill guide

3D print of bone model with 3D printed disposable drill guide

There is also developed software that allows to design personalised disposable surgical instruments. An example would be a tool for orthopaedics, which guides a drill at a fixed angle. It is designed in an environment that allows for measurements of angles and distances on three-dimensional model and thus to determine the appropriate axis. Such tool shortens surgical procedure, because physician does not need to determine drilling axis during procedure. Furthermore, operation precision is increased and thus patient's chances to faster recovery.

Another tool of that kind can be guide allowing decapitation of knee joint at the proper angle when procedure of knee replacement is performed.