Primary total hip arthroplasty with Duraloc cup in patients younger than 50 years: a 5- to 7-year follow-up study

Correlation of Cup Inclination Angle with Liner Wear for Metal-on-polyethylene in Hip Primary Arthroplasty

OBJECTIVES

The relationship between cup inclination angle and liner wear is controversial. Most authors in the published literature agree that the ideal cup inclination is associated with lower inner wear; however, some disagree. All previous studies did not control for femoral head diameter and inclination, so it is difficult to assess the relative or synergistic effects of cup angle on outcomes.

METHODS

We retrospectively reviewed 154 patients (171 hips) with primary total hip arthroplasties performed from 2001 to 2004. All surgeries had been performed by the same physician team. A posterior approach was applied in all patients. All prostheses were non-cemented cups with a 28-mm metal head. Inclusion criteria included that the radiographic material was not completed or lost for primary or last follow up. Patients were divided into four groups according to different cup inclination angle. There were 108 hips with inclination angles below 50°; 35 hips with angles between 50° and 55°; 17 hips with angles between 55° and 60°; and 11 hips with angles greater than 60°. An immediate postoperative radiograph was compared with a follow-up radiograph. Clinical and radiographic data were collected on standardized hip evaluation forms preoperatively, 6 months after surgery and at yearly follow-up visits. Radiographs were digitized and enlarged 100%. After the radiographs were digitized, polyethylene wear rates and acetabular cup abduction were measured on all patients with Cavas 15.0 software. The results were analyzed using Student's two-tailed paired t-test with SPSS 11.5.

RESULTS

The preoperative mean Harris hip score improved from 45.36 to 93.5 points 10 years after surgery. No acetabular component was revised for aseptic loosening. Three patients (three hips) had to undergo bone grafting and a lined arthroplasty for severe osteolysis around the acetabular component. The rate of implant survival at 10 years with respect to loosening was 100%. The mean liner wear rate was 0.135 mm/year in cups with inclination angles below 50°, 0.144 mm/year between 50° and 55°, 0.260 mm/year between 55° and 60°, and 0.403 mm/year when the angle was greater than 60°. Liner wear increased when the cup angle was larger than 55° (P < 0.05).

CONCLUSIONS

For metal-on-polyethylene prostheses, liner wear correlates with cup inclination angle larger than 55°. The ideal abduction angle for metal-on-polyethylene prostheses is less than 55°.

Higher wear-rate of third-generation metal-backed Reflection cups with eto-sterilised UHMWPE at a mean 13 years follow-up

Polyethylene (PE) wear and osteolysis is a recognised problem with non-cross linked PE liners and first generation modular cup designs. Wear particles induce osteolysis leading to aseptic loosening. We retrospectively compared the linear PE wear and implant survival and revision rates of the Reflection Cup and the Duraloc 300. After a mean clinical follow-up of 13 years (range 11-15 years), the 2D linear PE wear-rate of the Reflection liner (n = 68) was 0.23 mm/year, with a mean total wear of 3.14 mm (1.04-7.36), SD 1.45. The wear-rate of the Duraloc 300 cups (n = 32) was 0.14 mm/year, with a mean total wear of 1.84 mm (0.55-4.63), SD 1.07. The difference in PE wear-rate as well as mean total wear was highly significant (p = 0.0001). There was a positive correlation between wear-rate and both Oxford Hip Score and Harris Hip Score (p = 0.02). Large acetabular cup size (>54 mm), HA coating on the stem and age <50 years did not influence PE wear. The higher wear-rate in the Reflection liners could be related to the EtO sterilisation. Intermediate and long-term follow-up is advisable.

Cementless acetabular fixation in patients 50 years and younger at 10 to 18 years of follow-up

The purpose of the study was to evaluate the 10- to 18-year follow-up of cementless acetabular fixation in patients 50 years and younger. We retrospectively reviewed a consecutive group of 118 patients (144 hips) in whom primary total hip arthroplasty had been performed by 2 surgeons using a cementless acetabular component. Two (1.4%) cementless acetabular components were revised because of aseptic loosening. Twenty-four hips (16.7%) were revised for any mechanical failure of the acetabular component mostly related to acetabular liner wear and osteolysis. The average linear wear rate was 0.19 mm per year, which was higher than our previous reports with cemented acetabular fixation. The fiber mesh ingrowth surface of the cementless acetabular component in this study was superior to cemented acetabular components in terms of fixation. However, the high rates of wear and osteolysis have led to poor overall acetabular component construct survivorship.

Modular cementless cup for total hip arthroplasty: results at 4-year follow-up

The aim is to perform the assessment of a modular cementless acetabular cup with a tapered internal design for all bearing couplings. In 190 unselected consecutive patients, 207 total hip arthroplasties were implanted. The implants were clinically and radiographically evaluated. Follow-up was 49.7 ± 8.1 months. The average Harris hip score improved from 55.5 ± 5.7 to 94.7 ± 3.4 (P < 0.05). All cups were well-positioned and stable. The Kaplan-Maier cumulative survivorship was 98.5 ± 0.8%. No significant differences have been noted in dividing patients according to the different liner materials (P < 0.005). The study, whose rationale is the novelty of this kind of implant, suggests the efficacy of the Delta-PF acetabular cup.

Risk factors for revision of hip arthroplasties in patients younger than 30 years

BACKGROUND

Numerous reports of THAs in patients younger than 30 years indicate a high risk of revision. Although risk factors for revision have been reported for older patients, it is unclear whether these risk factors are the same as those for patients younger than 30 years.

QUESTIONS/PURPOSES

We therefore (1) determined function and survivorship of revision THAs performed in patients younger than 30 years, and (2) assessed the risk factors for revision THAs in this younger population by comparison with a group of patients younger than 30 years who did not undergo revision.

PATIENTS AND METHODS

We retrospectively reviewed the clinical records and radiographs of 55 patients younger than 30 years (average age at revision, 24.3 years; range, 14-30 years) who underwent 77 hip revisions. Revision was performed, on average, 4.6 years (range, 0.4-12 years) after the primary THA. The results for these 55 patients (77 revision THAs) were compared with results for a nonrevised group, including 819 THAs in patients younger than 30 years. Minimum followup of the revision group was 1 year (mean, 6.2 years; range, 1-15 years).

RESULTS

At followup after the revision, the Merle d'Aubigné-Postel score improved from 12.2 to 14.6. The rates of dislocation, neurologic lesions, and fractures were 15%, 7.8%, and 14%, respectively. The 10-year survival rate was 36% (95% confidence interval [CI], 21%-51%). Compared with the nonrevised group, the independent revision risk factors were young age at primary THA (OR 1.14 [1.07-1.19]), high number of previous surgeries (OR 5.41 [2.67-10.98]), and occurrence of at least one dislocation (OR 3.98 [1.74-9.07]). Hard-on-soft bearings had a higher risk (OR 3.42 [1.91-6.1]) of revision compared with hard-on-hard bearings.

CONCLUSIONS

Revision THAs are likely in patients younger than 30 years, and the complication rate is high. The survivorship of hip revision in this population is low and alternative solutions should be advocated whenever possible.

LEVEL OF EVIDENCE

Level III, therapeutic study, case control study. See the Guidelines for Authors for a complete description of levels of evidence.

Custom cementless stem improves hip function in young patients at 15-year followup

THA in young patients is challenging regarding restoration and survival because patients are young, active, and tend to have disturbed anatomy. We asked whether a three-dimensional custom cementless stem could restore hip function, decrease osteolysis and wear, and enhance stem survival in young patients. We retrospectively reviewed 212 patients (233 hips) younger than 50 years (mean, 40 years) at a followup of 5 to 16 years (mean, 10 years). The Merle D'Aubigné-Postel and Harris hip scores improved at last followup. No thigh pain was recorded for any of the patients; 187 of the 212 patients (88%) had full activity recovery, 206 had full range of motion, and 151 had a score greater than 80 points for all five categories of the Hip disability and Osteoarthritis Outcome score. Five patients had femoral osteolysis not associated with pain. With revision for any reason as an end point, the survivorship was 87% (range, 77%-97%) at 15 years, and considering stem revision only, the survivorship was 93% (confidence interval, 90%-97%) at 15 years. Our data compare favorably with those from series using standard cementless stems at the same followup with a high percentage of patients achieving functional restoration and a low rate of complications.

LEVEL OF EVIDENCE

Level IV, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.