Abstract
Purpose
This study analyzed the long-term results of cementless total hip arthroplasty using an extensively porous coated stem in patients younger than 45 years old.
Materials and Methods
The clinical and radiographic results of 45 hips from 38 patients who underwent cementless total hip replacement arthroplasty with an AML prosthesis were reviewed retrospectively. The average follow-up was 12 years (range, 10–15 years).
Result
The average Harris hip score was 87.3 (range77-94) points at the final follow-up. Hip scores at the last follow-up were; excellent in 32 out of 45 hips(71.1%), good in 10 (22.2%) hips and fair in 3(6.7%) hips. The prevalence of thigh pain was initially 15.6%(7 hips) and the pain in all hips disappeared 3 years after surgery.
Thirty-eight (84.4%) stems had good canal fill; 37 hips of these showed bone ingrowth and one hip had stable fibrous ingrowth. Seven (15.6%) hips had a poor canal fill. Four of these showed bone ingrowth, and 3 hips showed stable fibrous ingrowth. There was no unstable stem.
Osteolysis was observed around the stem in 20 hips(44.4%) and around the cup in 26 hips(57.8%). Most of the osteolysis in the femoral side was in zones I and VII.
Stress-mediated femoral resorption was observed in 30 hips at 3 years after surgery, 32 hips at 5 years after surgery and 33 hips (73.3%) at 10 years after surgery: first degree in 15 hips(33.3%), second degree in 11 hips (24.4%) and third degree in 7 hips(15.6%), respectively. The demographic data (age, weight and stem size) of the 35 hips showing evidence of stress shielding were compared with the group not showing stress shielding. There was no apparent difference between the two groups. The resorption did not progress to the third degree from either the first or second degree after 5 years postoperatively.
There was no stem loosening. Four hips were revised. One hip was revised at 5 years after surgery because of an unstable fixation of the acetabular component. Three hips were revised due to osteolysis around the cup and excessive polyethylene wear; posteoperative 10 years in two hips and 11 years in one hip.
Conclusion
The long term results of total hip arthroplasty using an extensively porous coated stem were acceptable, and there was no case involving the progression of proximal bone resorption.
