Source: Drug and Alcohol Review  |  Posted 8 years ago

Hydroxyapatite-coated stems show good clinical and radiographic outcome in patients undergoing total hip replacement, according to a recent Norwegian study.

A common problem with cemented hip prosthesis is aseptic loosening, particularly in men and younger patients. Studies have therefore focused on developing new cementless fixation techniques.

Hydroxyapatite (HA) is one of the most accepted bioactive materials used in prosthesis coating. Good short term clinical results have been obtained for HA coated prostheses, though long-term analyses are still needed. Furthermore, better results have been observed for HA coated stems than grit-blasted HA coated cups.

Dr. Olav Reikeras and colleagues at the National Hospital, Oslo, Norway, analysed the outcome of a grit-blasted and HA coated titanium stem designed for press-fit insertion. The study included 323 primary total hip replacements performed on 276 patients (189 women and 87 men) between the ages of 15 and 79 (average 48 years old). Radiographic and clinical examinations were performed 8 to 12 years after surgery.

Overall, only 1 stem needed revision and this was due to mechanical failure. Also, 42 press fit cups and 9 screw cups were revised, yet none were due to infection.

Osteolysis was found in 28 cases and was significantly associated with wear. Furthermore, 184 hips showed wear between 0.5 and 6.5 mm and wear was significantly associated with femoral head size.

In addition, minimal proximal bone loss was observed in 37 hips and distal bone hypertrophy in 23 hips.

Improvements were seen in motion, walking ability, and pain, particularly in thigh pain.

Dr. Reikeras concludes that this study "found very good clinical and radiographic results at a mean follow up of 10 years with a HA coated stem." Furthermore, "the wedge-shaped design of the stem may have provided a reliable primary stability for a rapid bone response with the HA."