Overview
Joint replacement surgery for hip dysplasia is often more complex than hip replacement for other conditions. Some of the reasons for increased complexity are:
- Distorted anatomy of the pelvis or thigh bone are common and may require special techniques – the shallow socket may require special implants or bone grafts to provide adequate support. The upper thigh bone may be displaced, twisted or have a small canal because of dysplasia.
- Younger patients – approximately one out of four hip replacement procedures before the age of fifty is because of hip dysplasia. These younger patients generally want to be more active and the artificial hip needs to last longer because of the younger age at time of surgery.
- Previous surgery is common and may require special attention. Even previous hip arthroscopy increases the complexity of total hip replacement in patients with hip dysplasia
- Leg length differences may be present and this can increase the complexity.
Mr Watson has had a year of specialised training in these complex operations
Hip joint replacement surgery is also called “total hip arthroplasty” or “total hip replacement”. This procedure uses artificial parts made of specialized metal, ceramic or very hard plastic to replace the damaged joint. While short-term results are similar to total hip replacements for other reasons, the long-term revision rate is worse for hip dysplasia patients. This is especially true for patients with more severe hip dysplasia.
When the dysplasia is more severe, or the patient is older, then a traditional total hip replacement is usually performed.
Hip dysplasia has unique features that need special techniques for hip replacement surgery as successful as possible. For surgical planning, hip dysplasia is usually classified from mild to severe with Type 1 being the least involved and Type 4 the most severe. Type 4 is when the hip is completely dislocated.
Lesser degrees of dysplasia still require special attention to get the best results. The anatomy of a dysplastic hip is different from the anatomy of other types of hip arthritis. The socket is more shallow than normal and may not be in the normal location. The upper part of the thigh bone may be small or abnormally shaped, and the legs may not be the same length. Previous surgical procedures during childhood may also cause difficulty in planning and performing a total hip replacement.
Placement of the socket is perhaps the most important part of total hip replacement for patients with hip dysplasia. The best results are usually obtained when the socket is placed as close as possible to the normal anatomical location. Pre-operative planning is especially important because dysplastic hips may be at a higher location than normal and need special techniques to be brought down to the normal level. Deepening of the socket is almost always needed and may require careful cracking of the inside wall of the pelvis combined with bone grafting to make sure the socket is placed deep enough that there is a good bone roof over the artificial socket.
Additional considerations are whether to use cement to hold the artificial parts in place, or whether to use special methods that allow bone to grow into the artificial parts without cement. This is especially important in hip dysplasia because patients tend to be younger than patients with other types of arthritis. In young patients there are some benefits to avoiding the use of cement if possible. Also, younger patients may need different types of surfaces for their artificial joints. Currently, the preferred artificial joint surfaces for young people tend to be ceramics, or metal on modern polyethylenes.
Adapted with permission from https://orthoinfo.aaos.org