Abstract
INTRODUCTION
The concept of anatomical stam is fit-and-fill in the proximity of the femur and to expect wall fixation, following to reduce thigh pain and stress shielding. Although the femoral medullary form and size are different in each races. CentPillar TMZF stem (stryker ®) is anatomical stem designed based on computer-tomography of Japanese femurs. The purpose of this study was to evaluate clinical and radiographic outcomes of CentPillar TMZF stem at a mean of 3.6 years postoperatively.
METHODS
We asseses the results of 98 primary total hip arthroplasty (THA) performed using a CentPillar TMZF stem in 91 Japanese patients (4 males, 94 females) undergoing surgery between August 2007 and June 2011, the mean age at the time of surgery was 62.0 (41–81) years old. The Diagnosis were osteoarthritis (OA) in 91 hips, rapidly destructive coxopathy (RDC) in 4 hips, rheumatoid arthritis (RA) in 3 hips. Clinical and radiographic assessments were performed for every patient for every follow up using Japan Orthopaedic Association (JOA) Score, thigh pain, revision surgery and complications. Radiographic assessments were including stem alignment on anteroposterior radiograph, stress shielding, bone remodeling, radiolucent line, osteolysis, loosening and subsidence.
RESULTS
50.7 points of the postoperative mean JOA score was significantly improved to 96.3 points postoperatively. No patients showed thigh pain. Intraoperative calcar fracture was occurred in 1 hip. In 97 hips of 98 hips (98%) stem was implanted in neutral position (within ±3 degrees). With regard to stress shielding, 69 hips (70%) had none or only 1st degree resorption; 29 hips (30%) had 2nd degree and no cases had 3rd and 4th degree. Spot welds were developed in 71 hips (71%; Gruen zone 2 and 6), and cortical hypertrophy were observed in 2 hips (2%; Gruen zone 3 and 5). No cases developed radiolucent line, osteolysis, loosening, and subsidence. No revision surgery were requied up to 5.8 years postoperatively.
DISCUSSION AND CONCLUSION
CentPillar TMZF stem provided a stable fixation, with excellent short-term clinical and radiographic outcomes. The strong proximal fixation was predictably enabled, and there were few cases fixed distal portion of the femur. These finding suggested CentPillar TMZF stem fits Japanese medullary form and can expect the long-term survival.
