Hip dysplasia, a congenital or early childhood developmental disorder of the hip joint, poses complex decisions for both patients and healthcare providers. Two common therapeutic approaches, periacetabular osteotomy (PAO) and implantation of a short-stem prosthesis, offer different advantages and challenges. This article highlights the indication criteria, advantages, and disadvantages, as well as the 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 results in instabilities and an increased risk of osteoarthritis. Typical symptoms include pain in the groin radiating to the thigh, knee, and lower back. In advanced stages, there is a progressive limitation of movement伴 with pain.

Periacetabular osteotomy (PAO)

Definition and objective

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

Procedure sequence

During the PAO, the bony acetabular part of the pelvis near the hip joint is controlledly severed at three locations in several steps. Subsequently, the acetabulum is aligned in a more optimal position, so that the femoral head is better covered. To stabilize the new acetabular position, metallic screws are used, which can usually remain in the body.

Goal of the PAO

• Improved biomechanics: Better alignment of the joint distributes the load more evenly, reducing wear and tear.
• Osteoarthritis prevention: Anatomical correction can slow or stop the progression of already beginning osteoarthritis.
• Preservation of the natural joint: Unlike prosthesis implantation, 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: The method is not suitable if there are already severe signs of wear.
• Adequate bone structure: A strong and healthy pelvis and hip bone is a prerequisite for the success of the operation.

Benefits of PAO

• Joint preservation: Avoidance of endoprosthetic replacement.
• Longevity: Aims for long-term reduction of osteoarthritis risk.

Disadvantages of PAO

• Long rehabilitation: Load-bearing only possible step by step.
• Technical complexity: High demands on the surgeon.
• Age limitation: Less suitable for older patients or advanced osteoarthritis.
• Difficult implantation of a later hip prosthesis: If endoprosthetic care becomes necessary at a later time, the previously performed PAO can change 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.

Aftercare

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

Short-stem prosthesis

Definition and objective

The short stem prosthesis is a modern form of endoprosthetics, in which the femoral neck is largely preserved. It is used for degenerative changes of the hip and offers a bone-sparing 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 rapid recovery and mobility exists.

Benefits of the short stem prosthesis

• Bone-preserving: Preserves the femoral neck.
• Rapid rehabilitation: Full weight-bearing often possible at an early stage.
• High success rate: Modern short-stem prostheses show impressive durability. Studies suggest that such prostheses can last 30 years or more without problems when indicated correctly. This means that the need for revision surgery has dropped dramatically.

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.

Aftercare

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

Comparison of the two procedures

Age and cartilage status

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

Professional and family-related stress

• Physically demanding occupations: Short-stem prosthesis allows for faster load-bearing capacity.
• Low-stress activities: PAO can offer long-term benefits.

Post-treatment duration

• PAO: Longer 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 is clearly preferred.

Modern developments in short-stem prosthetics

Hip arthroplasty has made enormous progress over the past few decades. In particular, short-stem prostheses have proven convincing through innovative design and material developments, such as modern articulating pairs with extremely low wear rates. These developments minimize the risk of implant loosening and ensure a lifespan of up to 30 years or more. The procedure is now also possible with minimally invasive techniques, yielding excellent results in terms of patient activity. Due to this success rate, the decision-making process is increasingly shifting in favor of short-stem prostheses, even in younger patients.

Conclusion

The choice between PAO and short-stem prosthesis depends on a variety of individual factors. While PAO is suitable for younger, active patients with preserved cartilage, short-stem prosthesis is a better choice for older patients with degenerative changes. Both procedures have their justification and should be carefully weighed considering the individual life situation, professional requirements, and health status. The decision is sometimes one of the most difficult in the field. However, with modern advances in endoprosthetics, the short-stem prosthesis has gained a remarkably high significance, as it offers a combination of longevity, bone-sparing design, and faster rehabilitation.