Hip Replacement

Artificial Hip Joint – Primary Total Hip Arthroplasty

 

The surgery of an artificial hip joint is performed with a minimally invasive technique. With this special technique, the muscle insertions remain completely preserved. Due to the smaller skin incision and subsequently to the reduced surgical trauma, the patients are able to mobilize in a very short time.

The digital planning helps the surgeon to easily find the correct position of the implants, equalizing leg length discrepancies and keeping the tension of the muscles in the correct way. At the Orthopaedic Clinic Gersthof approximately 400 such hip replacements are performed yearly.

 

The principal surgical steps performing total hip joint replacements are shown in the following illustrations:

 

1. Preoperative X-ray of the affected hip.

2. Preoperative digital planning of the implant position

3. Removal of the femoral head

4. Implantation of the new acetabular cup

5. The new acetabular part of the artificial hip consists of a metal cup and a liner made of ceramic or polyethylene

6. Reaming the femoral shaft for the stem position

7. The new shaft with the head

8. Implantation of the new prosthesis together with the femoral head

9. Postoperative X-ray

 

Revision-Surgeries for Hips

 

Failed total hip surgeries can have different reasons. Causes for revisions are:

  • Recurrent hip dislocation due to wrong position of parts of the implant
  • Aseptic loosening of the hip prosthesis
  • Periprosthetic deep joint infections
  • Periprosthetic fractures 

 

Due to these complications bone defects at the area of the prosthesis are possible.

These bone defects at the acetabular site are treated by using different cups, metal blocks in combination with screws and various kinds of cages in combination with a cup.

  1. Preoperative X-ray: Dislocated implant with a huge acetabular bone defect
  2. Cup and Cage reconstruction which means that the cup is supported by a cage (the cage is fixed with screws)

 

The most modern technique for big bone defects at the acetabular site is the use of individually made implants. Previous to the surgery, the bone defects are being analyzed with a computer tomogram. By the use of this computer tomogram a perfectly designed 3D model of the patient’s hip is created. This fits like a glove to the hand and has a perfect form-fit to the bone defect of the acetabulum.

 

  1. The preoperative X-ray shows a massive aseptic loosening of the acetabular cup (right side) with a shortening of the left leg (3 cm difference).
  2. The preoperatively made 3D model shows the defect and the quality of the bone.
  3. With the use of a computer tomogram a 3D model of the pelvis is created. The new prosthesis fits exactly to the bone structure of the patients defect
  4. Guiding rings help to find the perfect position of the screws. With this method, the screws can be placed into the best bone quality
  5. The prosthesis is created with a 3D printing method
  6. The postoperative X-ray shows a solid fixation of the implant and the reconstruction of the previous leg length discrepancy

 

Defects at the femoral shaft are covered by different lengths and designs of the stem prosthesis.

Knee Replacement

Artificial Knee Joint – Primary Total Knee Arthroplasty

 

Total knee replacements are performed in the standard procedure but can also be executed with modern techniques like patient specific cutting blocks. At the Orthopaedic Clinic Gersthof approximately 450 total knee replacements are performed yearly.

For the patient specific cutting blocks we use the VISIONAIRE technology. To be able to create such a patient specific cutting block, the patient needs previous to the surgery a x-ray of the whole limb and a magnetic resonance imaging (MRI) of the knee. The aim of this special technology is to reconstruct the bone axis in a 3 dimensional way and to find the adequate sizes and the position of the implants. Every individual cutting block fits perfect to the surface structure of the knee. Every cutting block has a cutting slot, in which the bone cut is performed. This method helps to create a stable and straight knee. In this way the knee prosthesis can be implanted perfectly.

 

  1. The patient matched cutting blocks fit exactly to the surface of the knee (Visionaire® Technology – Smith & Nephew™)
  2. The figures show the patient matched cutting block for the femur and the tibia
  3. The next image shows the comparison between the preoperative planning and the postoperative X-ray
  4. The mechanical axis of the limb is perfectly reconstructed and meets the middle of the hip, knee and ankle joint

 

Primary knee implantation in case of severe deformities

 

  1. Huge bone defect on the lateral and femoral condyl
  2. The bone defect results in a massive valgus knee
  3. Postoperative X-ray
  4. Postoperative longstanding X-ray
  5. Knee function in extension
  6. Knee function in flexion
  7. Well aligned axis of the whole limb

Revision-Surgeries for Knees

 

Failed total knee arthroplasties can have many reasons. Some of those are:

  • Shaky and instable knee joints

  • Aseptic loosening of the knee prosthesis

  • Deep infections

  • Bone fracture at the implant area (e.g. after accident)

  • Knee stiffness after total knee arthroplasty

  • Metal allergies etc.

 

If some of these above mentioned problems occur, a revision surgery is necessary. The following surgical factors have to be considered:

 

  • Bypassing of possible bone defects

  • Obtaining the correct and stable knee joint in flexion and extension

  • Adequate fixation of the prosthesis with stemmed implants

 

Images of a Revision surgery of the knee

  1. The preoperative X-ray prior to the revision shows a cement spacer – implanted for a period of 3 months for healing the deep periprosthetic joint infection

  2. X-ray after revision surgery

  3. Video showing the successful result

 

 

Different metal augments in combination with a prosthesis are used for bypassing various bone defects. The status of the ligament stability of the knee leads the surgeon to use different degrees of the couple mechanism of the prosthesis. Theat means that the connection of the femoral prosthesis and the lower leg prosthesis (inlay and tibia prosthesis) can be different and is adjusted to preserve a stable knee.

 

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