Objectives. The Swedish National Total Hip Arthroplasty Register, initiated in 1979, describes the epidemiology of total hip replacement (THR) in Sweden. The objective of this study was to describe the epidemiology, demographics and to perform an outcome analysis on patients, younger than 55 years, who underwent a total hip replacement in Sweden between 1992–2002. Methods. From the Swedish National Total Hip Arthroplasty Register 11579 patients, younger than 55 years at the time of surgery, were identified who had undergone a primary total hip replacement from 1992–2002. The patients selected were checked with the Swedish Cause of Death Register (CDR), based on the unique identification number used in Sweden, to ensure that only living patients were addressed. Epidemiological and demographical analysis was then performed using SPSS (SPSS Inc, Chicago, IL). Outcome. 11362 patients were identified. 5260 (46,3 %) men and 6102 (53,7 %) women, the mean age was 48, 2 years (14–55). The indication for surgery was in over 60% of the cases Osteoarthrosis (OA) but over-represented diagnosis, when compared to the remaining THR operations in Sweden, were arthritis, osteonecrosis and sequele after childhood disease. The most common fixation technique used was cemented total hip replacement in 6160 (54,2 %) followed by Hybrid 2442 (21,5 %) and uncemented 2235 (19,7 %) technique. Survival for cemented, uncemented and hybrid implants in male patients with Osteoarthrosis after 10 years was 65,8 % (+/− 2,6%), 66,6 % (+/− 2,9%) and 64,0 % (+/− 3,0 %) respectively. In the arthritis group the survival was slightly better with a 10 year survival of 72,8 % (+/− 3,6%), 66,8 % (+/− 5,9%) and 71,5 % (+/− 7,5%) respectively, male patients had a slightly inferior outcome compared to females across all diagnosis groups. Conclusions. This young cohort is epidemiologically and demographically different than the older one previously studied in the Swedish National Hip Register. Survival analysis shows that 10 year survival in this population is considerably worse than for the older cohort. Patients with arthritis fare better than patients with Osteoarthrosis and females have superior outcome to males. In this study the mode of implant fixation did not appear to influence survival in patients with OA, however it does seem to affect the outcome in patients with inflammatory arthritis. This study shows that the outcome in this patient category is poor when compared with the older THR patients. There is an obvious need to increase use of alternative and conservative methods in treatment of the young patient with degenerative hip disease. Continuous research and referral of the young patients to dedicated centres is recommended.

Metal-metal total hip replacements were commonly used in the 1960’s and early 1970’s. Failures usually occurred as a result of aseptic loosening although many of these implants provided long term function similar to metal-UHMWPE bearings.

Metal-metal bearings used in total hip arthroplasty are made of cobalt chrome. The volume of wear generated from a metal-metal bearing is considerably less than that from a metal-UHMWPE bearing. Factors which may affect the metal-metal wear rates include the clearance (difference in radius between the femoral head and acetabular bearing surface), surface roughness, and carbon content of the cobalt chrome alloy. A small clearance provides more contact area between the two surfaces which decreases contact stress while a large clearance permits more fluid flow into the joint. If the clearance is too small, and exceeds manufacturing tolerances, the joint articulation may become excessively tight and equatorial rather than polar contact occurs between the bearing surfaces which can increase frictional torque and cause loosening. This has been implicated as a cause of failure of the McKee-Fararr metal-metal hip replacements. Wear is also increased with increased surface roughness but the effect of other material variables such as cast vs. forged and carbon content are less clear.

Early clinical results with modern metal-metal hip replacements demonstrate clinical results which are comparable to metal-UHMWPE bearings and less aseptic loosening than metal-metal designs used in the 1960’s and 1970’s. However, concerns with metal-metal hip replacements include the generation of metal particulate debris which may travel to the distal sites as well as local osteolysis.

In patients with metal-polyethylene total joint replacements, metal as well as polyethylene particles can be found at distant sites. Urban et al. (1) reported that in a study of postmortem specimens from patients with metal-polyethylene total joint replacements, metallic wear particles were identified in the para-aortic lymph nodes in 68 percent and in the liver or spleen in 38 percent of the patients. The serum and urine levels of cobalt and chromium are elevated in patients with metal-metal articulations. Metals can travel to distant sites in ionic form and little is known about the long term clinical effects of elevated serum and urine metal levels. Cancer risk has not been shown to be increased in patients who have received metal-metal hip replacements. However, long term studies with large numbers of patients are needed to accurately asses this risk.

Aims

Young adults undergoing total hip arthroplasty (THA) largely have different indications for surgery, preoperative function, and postoperative goals compared to a standard patient group. The aim of our study was to describe young adult THA preoperative function and quality of life, and to assess postoperative satisfaction and compare this with functional outcome measures.

Introduction

Modular dual mobility (MDM) prostheses are increasingly utilized for total hip arthroplasty (THA) to mitigate the risk of postoperative instability in high risk patients. Short-term reports on clinical outcomes are favorable but there are few studies on young active patients. This study quantified proximal femoral stress shielding and metal ion release in MDM combined with modern cementless stem design in young active patients.

Aims

Modular dual mobility (DM) prostheses in which a cobalt-chromium liner is inserted into a titanium acetabular shell (vs a monoblock acetabular component) have the advantage of allowing supplementary screw fixation, but the potential for corrosion between the liner and acetabulum has raised concerns. While DM prostheses have shown improved stability in patients deemed ‘high-risk’ for dislocation undergoing total hip arthroplasty (THA), their performance in young, active patients has not been reported. This study’s purpose was to assess clinical outcomes, metal ion levels, and periprosthetic femoral bone mineral density (BMD) in young, active patients receiving a modular DM acetabulum and recently introduced titanium, proximally coated, tapered femoral stem design.

To assess clinical outcomes, metal ion levels, and periprosthetic femoral bone mineral density (BMD) in young, active patients receiving a modular dual mobility acetabulum and recently introduced titanium, proximally coated, tapered femoral stem design.

This was a prospective study of patients  65 years of age, with a BMI  35 kg/m², and UCLA activity score > 6 who received a modular cobalt chrome acetabular liner, highly cross-linked polyethylene mobile bearing, and cementless titanium femoral stem for their primary THA. Patients with a history of renal disease and metal hardware elsewhere in the body were excluded. All patients had a minimum of 2-year clinical follow-up.

Patient reported outcome measures, whole blood metal ion levels (ug/L), and periprosthetic femur BMD were measured at baseline and at 1- and 2-years postoperatively.

43 patients (30 male, 13 female; mean age 52.6 ± 6.5 years) were enrolled. Harris Hip Scores improved from 54.1 ± 20.5 to 91.2 ± 10.8 at 2 years postoperatively (p<0.001). All patients had radiographically well-fixed components, no patients have sustained an instability event, and no patients have required a return to the operating room or revision procedure.

Mean cobalt levels increased from 0.065 ± 0.03 ug/L preoperatively to 0.30 ± 0.51 at 1-year postoperatively (p=0.01), but decreased at 2 years postoperatively to 0.16 ± 0.23 (p=0.2) (Table 1). Four patients (9.3%) had a cobalt level outside the reference range (0.03 to 0.29ug/L) at 2 years postoperatively with values from 0.32 to 0.94. None were symptomatic

The mean femoral BMD ratio was maintained in Gruen zones 2 thru 7 at both 1- and 2-years postoperatively using this stem design (Table 2). At 2 years postoperatively, BMD in the medial calcar was 101.5% of the baseline value.

Use of a modular dual mobility prosthesis and cementless, tapered femoral stem has shown encouraging results in young, active patients undergoing primary THA. Elevation in mean cobalt levels and the presence of four patients outside the reference range at 2 years postoperatively demonstrates the necessity of continued surveillance in this cohort.

For any figures or tables, please contact authors directly: barrackr@wustl.edu

Background. Because of the long life expectancy of young total hip arthroplasty (THA) patients and the limited durability of prosthetic implants in young patients, surgeon's always must take into account that the primary THA will be revised in the future. Therefore, not only the survival of the primary total hip in young patients is important, but we would also like to accentuate the revisability of a primary THA in this specific and high demanding patient population. Methods. Based on our philosophy, we always use cemented hip in young patients, if needed with acetabular bone impaction grafting. 343 consecutive cemented THA in 270 patients under the age of 50 years were evaluated, all implanted between 1988 and 2006. We also assessed the results of the revised THA (n=53) within the same population. Clinical, radiographical and survival of primary and revision THA were evaluated. Outcome. Survival analysis of all 343 hips with endpoint revision for any reason of either component showed a survival of 86% after 10 years. Survival of the stem and cup with endpoint aseptic loosening 93% after 10 years. Remarkably, the THA in which the cemented cup was combined with acetabular bone impaction grafting had a survival of 90% (SE 2.8) in contrast to a survival of 82% (SE 3.4) of the cups without an acetabular revision with endpoint revision for any reason of the whole prostheses(log-rank test, p=0.156) at 10 years. With no patient lost during follow-up, 53 primary hips were revised after a mean follow-up of 8.9 (range 2.0–19.3) years. The average follow-up of the revision THA was 4.2 (range 0.1–14.8) years. Three hips of this revision cohort needed a repeat revision, two had a reinfection after a septic revision and one revised cup failed 12 years after revision. The survival of the revised cohort with endpoint revision for any reason was 91% after 5 years, with endpoint aseptic loosening the survival at 5 years was 100 %. As well after primary as revision THA good clinical outcome scores were measured. Interpretation. Cemented implants in young patients showed satisfying results in primary as well as after revision THA with very acceptable survival and clinical outcomes. Keeping in mind that the young patient will outlive their primary THA, the primary hip has to be revisable and the results of the revision THA must be as good as the primary THA. Bone defects both in primary and revision THA can be successful managed with impacted bone grafts, without the need for augments, cages or larger implants

The October 2013 Hip & Pelvis Roundup³⁶⁰ looks at: Young and impinging; Clothes, weather and femoral heads?; Go long, go cemented; Surgical repair of the abductors?; Aspirin for DVT prophylaxis?; Ceramic-on-polyethylene: a low-wear solution?; ALVAL and ASR™: the story continues….; Salvaging Legg-Calve-Perthes’ disease