In 2005, we demonstrated that the polished triple-tapered C-stem at two years had migrated distally and rotated internally. From that series, 33 patients have now been followed radiologically, clinically and by radiostereometric analysis (RSA) for up to ten years. The distal migration within the cement mantle had continued and reached a mean of 2 mm (0.5 to 4.0) at ten years. Internal rotation, also within the cement mantle, was a mean 3.8° (external 1.6° to internal 6.6°) The cement mantle did not show any sign of migration or loosening in relation to the femoral bone. There were no clinical or radiological signs indicating that the migration or rotation within the cement mantle had had any adverse effects for the patients.

Cite this article: Bone Joint J 2014;96-B:604–8.

In a series of 450 patients over 70 years of age with displaced fractures of the femoral neck sustained between 1995 and 1997 treatment was randomised either to internal fixation or replacement. Depending on age and level of activity the latter was either a total hip replacement or a hemiarthroplasty. Patients who were confused or bed-ridden were excluded, as were those with rheumatoid arthritis. At ten years there were 99 failures (45.6%) after internal fixation compared with 17 (8.8%) after replacement. The rate of mortality was high at 75% at ten years, and was the same in both groups at all times. Patient-reported pain and function were similar in both groups at five and ten years. Those with successfully healed fractures had more hip pain and reduction of mobility at four months compared with patients with an uncomplicated replacement, and they never attained a better outcome than the latter patients regarding pain or function.

Primary replacement gave reliable long-term results in patients with a displaced fracture of the femoral neck.

Introduction: The C-stem (DePuy, Leeds, UK) is triple tapered, polished and collarless. These features can facilitate distal stem migration within the cement mantle, a phenomenon first noticed on radiographs and later confirmed by radiostrereometric analysis (RSA) for the double tapered polished Exeter stem (Stryker, Mahwah, NJ). Low revision rates are reported for the Exeter stem and the view that early migration predicts later failure has not been confirmed with double tapered designs. If a triple tapered stem has any advantages is however not known

Patients and methods: 33 primary hip arthroplasties with a median age of 66 (46–74) years were followed for 2 years with radiostereometric analysis (RSA) at 3 months, 6 months, 1, 2 and 3 years. The diagnosis was primary osteoarthrosis in all hips. Both migration and rotation were studied.

Results: All the stems migrated distally and posteriorly within the cement mantle. The median distal migration was 1.47 mm at 3 years and the median posterior migration was 1.56 mm at 3 years. All the stems rotated towards retroversion and median rotation at 3 years was 2.0°. For all the other directions the prosthesis was stable up to 3 years

Discussion: The C-stem migrates and rotates more than cemented prostheses of other designs. Compared with other tapered prostheses the distal migration is at the same level but posterior rotation is higher and furthermore it migrates posteriorly, which the other tapered stems do not. If this migration/rotation pattern is tolerable without risk of prosthetic failure needs to be studied further, but at present there is no indication from the available clinical results for the C-Stem that this pattern is deleterious.

We investigated the wear characteristics and clinical performance of four different total hip joint articulations in 114 patients. Wear and migration was measured by roentgenstereophotogrammetric analysis at five years or at the last follow-up. The mean annual wear was 0.11 mm for a stainless steel/Enduron articulation, 0.34 mm for stainless steel/Hylamer cup, 0.17 mm for zirconium oxide ceramic/Enduron and 0.40 mm for zirconium oxide ceramic/Hylamer. The difference between the groups was significant (p < 0.008) except for stainless steel/Hylamer vs zirconium oxide ceramic/Hylamer (p = 0.26).

At present, 12 patients have undergone a revision procedure, four at five years and eight thereafter. No patient who received a stainless steel/Enduron articulation at their primary replacement required revision.

Conflicting results have been reported about the performance of the zirconium oxide ceramic femoral head, but our findings suggest that it should not be used with a polymethylmethacrylate acetabular component. Hylamer has already been withdrawn from the market.

We used roentgen stereophotogrammetric analysis to follow 33 C-stem femoral components for two years after primary total hip arthroplasty. All components migrated distally and posteriorly within the cement mantle. The mean distal migration was 1.35 mm (sd 0.62) at two years and the mean posterior migration was 1.35 mm (sd 0.69) at two years. All the femoral components rotated into retroversion with a mean rotation at two years of 1.9° (sd 1.1). For all other directions, the prosthesis was stable up to two years. Compared with other tapered prostheses, the distal migration of the C-stem is the same, but posterior rotation and posterior migration are greater.

It remains a matter of debate whether displaced fractures of the neck of the femur should be treated by internal fixation or arthroplasty. We have compared the two methods with regard to complications, mortality and functional outcome.

We studied 409 patients, aged 70 years and over, with subcapital fractures graded as Garden 3 or 4, in a two-year prospective multicentre study from 12 Swedish hospitals. They were randomised to internal fixation or arthroplasty. Patients who were mentally confused, bedridden or in a nursing-home were excluded from the survey.

After two years the rate of failure was 43% in the internal fixation (IF) and 6% in the arthroplasty group (p < 0.001). In the IF group 36% had impaired walking and 6% had severe pain compared with 25% and 1.5%, respectively, in the arthroplasty group (both p < 0.05). There was no difference in mortality.

With a high rate of failure and poor functional outcome after IF, we recommend primary arthroplasty for displaced fractures of the neck of the femur in patients over 70 years of age.