Total Hip Replacement via DAA — What are the Risk Factors?

Overview

The direct anterior approach for total hip replacements is a safe, effective method that has been used for over 30 years. Whilst it has an extremely favourable risk profile, like all operations, there are risks. Some are unique to the DAA, whilst others are likely to be reduced due to its internervous and intermuscular nature.

Bleeding

Blood loss in any major surgery is inevitable. The rate of blood transfusion requirement after a DAA hip replacement is approximately 1%, unless other conditions cause increased bleeding or you are on blood thinners. It is important to disclose all medications including natural remedies such as ginger, glucosamine, and fish oil, as these can increase bleeding. Banking your own blood is a possibility but is unlikely to be required.

Infection

A risk of infection is present any time the skin is cut. For a hip replacement, the national average is approximately 1–2%, and is dependent on many factors. If you have diabetes, are a smoker, or are immunocompromised, additional antibiotic cover may be needed. After your total hip replacement, intravenous antibiotics are given for 24 hours, reducing your infection risk significantly.

Dislocation

The worldwide risk of dislocation ranges from 0.5–10% depending on the series and time period studied. The anterior approach is suggested to be more stable than other approaches as no muscles are cut, and the surrounding tissues are not compromised.

In the DAA, there are no post-operative restrictions within reason — you can sit in a normal chair, toilet seat, cross your legs, and bend down to pick things up. Patient factors that increase dislocation risk include nerve palsies, Parkinson's disease, muscle weakness, and poor balance. A Dual Mobility prosthesis can be considered for high-risk patients.

DVT and Pulmonary Embolism

Deep venous thrombosis and pulmonary embolism can occur after hip replacement. Dr Liew uses multiple modalities to decrease risk, including TED compression stockings (worn 24/7 for 2 weeks), foot pumps immediately after surgery, and a pharmacological agent starting the day after surgery.

Symptoms of a blood clot include worsening calf pain with swelling or redness, shortness of breath, or cough with blood staining. These are emergencies requiring urgent investigation and treatment.

Nerve Damage

In the direct anterior approach, the nerve at risk is the lateral femoral cutaneous nerve of the thigh — a purely sensory nerve that does not supply any muscle. The worst case is a loss of sensation on the side of the thigh in a patch of skin the size of a hand. In most cases this returns by the 3-month mark. When permanent, it does not cause any functional issues with the hip or walking.

Fracture and Loosening

Fracture: Whenever an implant is placed into bone, the bone can break, particularly with severe osteoporosis. A small fracture to the greater trochanter can be treated non-operatively and almost always heals without intervention, slowing recovery by 6–8 weeks.

Loosening: Implants can become loose after many decades, accelerated by chronic low-grade infection, subtle movement in the bony bed, or wear of the plastic liner. One hallmark of a loose prosthesis is pain at the start of walking that goes away after a few steps. Dr Liew believes in following hip replacements for life so issues can be identified and addressed early.