THA in Hip Dysplasia: Acetabular and Femoral Reconstruction
Total hip arthroplasty (THA) in younger patients with hip dysplasia carries a higher risk for dislocation, earlier loosening, and neurovascular injury than THA in older patients without dysplasia. When considering THA for these younger patients, Robert Trousdale, MD, from Mayo Clinic, Rochester, Minnesota, says the surgeon should factor in:
- Deficiency of the acetabular lateral bone
- Excessive femoral anteversion
- Leg shortening and sciatic nerve tension
- The patient’s age
THA in the patient with hip dysplasia typically involves acetabular and femoral reconstruction. The acetabulum is traditionally replaced using cemented sockets, but this method has been associated with poor long-term outcomes. Some surgeons, including Dr. Trousdale, prefer uncemented sockets for THA.
For all hip dysplasia patients, Dr. Trousdale recommends putting the cup in the native acetabular position, rather than the position dictated by the patient’s bone deficiency. He also uses supplemental screws to keep the implanted socket in place, especially in patients with a deficient acetabulum.
For patients who have a lateral bone deficiency, Dr. Trousdale advises medializing the hip center to the medial wall and accepting some lateral uncoverage (~1.5 cm of the socket) and a slight elevation of the hip center. Importantly, he recommends using a bone autograft only in young patients with severe deformity.
If femoral reconstruction is needed, the most appropriate femoral implant should be selected for each patient. For example, Dr. Trousdale advises using proximally coated stems only in patients with mild deformity because these stems fit poorly and may cause anteversion and fracture in more severe deformity. Although fully coated stems allow a degree of adjustment for anteversion, Dr. Trousdale considers them less appropriate for young, active patients.
Dr. Trousdale favors modular uncemented femoral stems for patients with dysplasia, as these stems permit maximum adjustment for anteversion and metaphyseal/diaphyseal size mismatch. One study of 28 patients in which THA was performed with modular uncemented stems showed an almost two-fold increase in the Harris Hip Score at 2 to 5 years’ follow-up. All stems had bony ingrowth and none required revision.
Overall, Dr. Trousdale believes THA is a very effective procedure in patients with hip dysplasia, providing improved function and dramatic pain reduction. With the introduction of new techniques and implants, the procedure should become simpler and lead to even better outcomes in the future.
Dr. Trousdale’s presentation from Current Concepts in the Management of Hip Disorders, a pre-course organized by the International Congress for Joint Reconstruction for the Mid-America Orthopaedic Association’s annual meeting, can be found here.