Hip dysplasia, a congenital or early childhood malformation of the hip joint, presents both patients and healthcare providers with complex decisions. Two common treatment approaches, periacetabular osteotomy (PAO) and short-stem prosthesis implantation, offer different advantages and challenges. This article examines the indications, advantages and disadvantages, and suitable patient groups for these methods.

What is hip dysplasia?

Hip dysplasia is a malformation of the hip socket (acetabulum) in which the socket does not adequately cover the femoral head. This leads to instability and an increased risk of osteoarthritis. Typical symptoms include groin pain radiating into the thigh, knee, and lower back. In advanced stages, painful limitations in movement become increasingly common.

Periacetabular osteotomy (PAO)

Definition and objectives

Periacetabular osteotomy (PAO) is a surgical procedure for treating hip dysplasia that aims to preserve natural joint function by reshaping the pelvic bone. Developed by Professor Reinhold Ganz, the procedure is characterized by its joint-preserving philosophy.

Procedure

During PAO (percutaneous acetabular osteotomy), the bony part of the acetabulum near the hip joint is carefully cut at three points in several steps. The acetabulum is then repositioned to provide better coverage of the femoral head. Metallic screws, which can usually remain in the body, are used to stabilize the new acetabular position.

The goal of the PAO

• Improved biomechanics: The better alignment of the joint distributes the load more evenly, which reduces wear and tear.
• Osteoarthritis prevention: Anatomical correction can slow down or stop the progression of osteoarthritis that has already begun.
• Preservation of the natural joint: Unlike with the implantation of a prosthesis, the patient's own hip joint is preserved.

Indication criteria

The PAO is particularly suitable for:

• Younger patients (15-40 years) with stable cartilage conditions.
• Mild to moderate osteoarthritis: This method is not suitable if there are already severe signs of wear and tear.
• Sufficient bony structure: A strong and healthy pelvic and hip bone is a prerequisite for the success of the operation.

Advantages of PAO

• Joint-preserving: Avoidance of endoprosthetic replacement.
• Longevity: Aims for a long-term reduction in the risk of osteoarthritis.

Disadvantages of PAO

• Long rehabilitation: Load-bearing capacity can only be achieved gradually.
• Technical complexity: High demands on the operator.
• Age restriction: Less suitable for older patients or those with advanced osteoarthritis.
• Increased difficulty in implanting a later hip prosthesis: Should endoprosthetic treatment become necessary at a later date, the previously performed PAO can alter the anatomy of the hip joint in such a way that the prosthesis implantation is technically more difficult and associated with a higher risk of complications.

Post-treatment

1. Gradual increase in weight load: Initially, only partial weight load (approx. 20-30 kg) is permitted. Full weight-bearing capacity is achieved gradually over weeks or months.
2. Physiotherapy: Intensive mobilization to restore joint function.
3. Long-term monitoring: Regular follow-up examinations to ensure the success of the treatment.

Short stem prosthesis

Definition and objectives

The short-stem prosthesis is a modern form of endoprosthetics in which the femoral neck is largely preserved. It is used in cases of degenerative changes in the hip and offers a bone-conserving alternative to the standard prosthesis.

Indication criteria

A short stem prosthesis is suitable for patients who:

• Pre-existing osteoarthritis or other degenerative changes are present.
• The desire for a quick recovery and mobility exists.

Advantages of the short stem prosthesis

• Bone-saving: Preserves the femoral neck.
• Rapid rehabilitation: Full weight-bearing is often possible early on.
• High success rate: Modern short-stem prostheses demonstrate impressive durability. Studies suggest that, with proper indication, such prostheses can now last 30 years or more without problems. This means that the need for revision surgery has drastically decreased.

Disadvantages of the short stem prosthesis

• Implant wear: Despite modern materials, loosening remains theoretically possible in the long term.
• No joint-preserving option: The natural femoral head is removed.
• Lifespan: May be limited depending on the load.

Post-treatment

• Mobilization usually begins on the first postoperative day.
• Continuous physiotherapy for optimal mobility and muscle building.

Comparison of the two methods

Age and cartilage status

• Younger patients (< 40 years): Joint preservation through PAO recommended.
• Older patients (> 60 years): Short stem prosthesis is more appropriate due to degenerative changes.

Professional and family stresses

• Physically demanding professions: Short-stem prostheses allow for faster recovery.
• Low-stress activities: PAO can offer long-term benefits.

Post-treatment duration

• PAO: Extended rehabilitation with partial weight-bearing.
• Short stem prosthesis: Early full weight-bearing possible.

Pre-existing osteoarthritis

• Mild or no osteoarthritis: PAO can show good results.
• Advanced osteoarthritis: Short stem prosthesis clearly preferred.

Modern developments in short stem prosthetics

Hip replacement surgery has made enormous progress in recent decades. Short-stem prostheses, in particular, impress with innovative design and material developments, such as state-of-the-art bearing surfaces that exhibit extremely low wear. These developments minimize the risk of implant loosening and ensure a lifespan of up to 30 years or more. Furthermore, the procedure can now be performed minimally invasively, with excellent results regarding patients' activity levels. Due to this success rate, many patients, even younger ones, are increasingly opting for short-stem prostheses.

Conclusion

The choice between a periaretoarth (PAO) and a short-stem prosthesis depends on a variety of individual factors. While PAO is suitable for younger, active patients with preserved cartilage, a short-stem prosthesis is the better choice for older patients with degenerative changes. Both procedures have their merits and should be carefully considered, taking into account the individual's life circumstances, professional demands, and overall health. This decision is sometimes one of the most difficult in the field. However, with modern advances in endoprosthetics, the short-stem prosthesis has gained considerable prominence, offering a combination of longevity, bone-conserving design, and faster rehabilitation.