Similar outcome with a new anteverted or a straight standard stem: a randomized study of 72 total hip arthroplasties evaluated with clinical variables, radiostereometry, and DXA up to 2 years

Abstract

Background and purpose The anatomical uncemented stem, SP-CL (Static Physiologicus – CementLess), designed to facilitate insertion and to avoid stress concentration at solitary contact points, has been on the market since 2014 but is not well documented. We studied its clinical performance, migration, and associated bone remodeling in a randomized controlled trial, with the Corail stem as control. Patients and methods 79 patients (80 hips) were primarily recruited and 71 patients (72 hips, 36 SP-CL, 36 Corail) attended the last follow-up at 2 years. The Oxford Hip Score (OHS) was the primary outcome. In addition, we assessed stem migration, changes in bone mineral density, and development of radiolucencies by RSA, DXA, and conventional radiography. Results At 2 years Oxford Hip Score was similar between the SP-CL and Corail stem. At 2 years the SP-CL stems showed a median distal migration of 0.23 mm (−0.1 to 5.2) and the Corail stems of 0.11 mm (−0.4 to 4.4). The SP-CL stems showed slightly more loss of bone mineral density in Gruen region 7 (p = 0.003). Interpretation We found no difference in clinical results between the SP-CL and the well-documented Corail stem. The same stem stability was reached between 1 and 2 years postoperatively for both stems. As a next step we think that the SP-CL stem should be studied in a multi-center setting, before being accepted for general use.

Evaluation of Proximal Femoral Bone Mineral Density in Cementless Total Hip Arthroplasty

“…The temporal changes in BMD over the perioperative period in our RCT indicated that a substantial change in the loading pattern occurred for all stem designs in the first 6 weeks. This is further supported by migration studies using radiostereometric analysis, which have identified a longer remodeling period of 3 to 6 months postoperatively until stable implant fixation is achieved in cementless THA 10,28 . This adaptive remodeling period justified our decision to measure BMD changes from preoperative levels, and we advocate for use of this method in future studies.…”

Contact states with femoral cortical bone and periprosthetic bone mineral density changes differ between traditional and newly introduced fully hydroxyapatite-coated stems

“…8 The preservation of bone around the stem has been shown to be better when using the T-HA stem compared with other designs of stem in several comparative studies. [4][5][6] Slullitel et al 4 reported that the CORAIL stem provided better preservation of the proximal femoral bone than the short proximally porous-coated stem, in a randomized controlled trial (RCT). Two other RCTs using DEXA showed a significantly higher loss of BMD in the proximal Gruen zones with an anatomical stem featuring a plasma spray coating of calcium phosphate and a femoral neck-preserving short stem, compared with the CORAIL stem.…”

“…Two other RCTs using DEXA showed a significantly higher loss of BMD in the proximal Gruen zones with an anatomical stem featuring a plasma spray coating of calcium phosphate and a femoral neck-preserving short stem, compared with the CORAIL stem. 5,6 Uncemented stems show a rapid loss of periprosthetic BMD in the first postoperative year, and thereafter it declines in direct proportion with the age of the patient. 3,21 The periprosthetic BMD in zone 6, one and two years postoperatively, with the T-HA stem in our study increased from baseline.…”

“…Two other RCTs using DEXA showed a significantly higher loss of BMD in the proximal Gruen zones with an anatomical stem featuring a plasma spray coating of calcium phosphate and a femoral neck-preserving short stem, compared with the CORAIL stem. 5,6…”

“…Several authors have reported better conservation of bone around fully HA-coated stems than around other designs of stem. [4][5][6] Several manufacturers have recently introduced various designs of fully HA-coated stems. Excellent long-term results and conservation of bone around the stem have been reported following THA using a traditional fully HA-coated stem (T-HA).…”