In-line Pullout Strength of 2 Acetabular Fixation Methods for Ligamentum Teres Reconstruction of the Hip: A Cadaveric Study

Background: Ligamentum teres (LT) reconstruction is an appropriate alternative in select cases of LT full-thickness tears, resulting in hip micro- or macroinstability. Graft fixation at the acetabular fossa is critical to achieving the best functional results. Purpose: The purpose of this study is to compare the pullout strength of 2 graft fixation methods used for LT reconstruction of the hip. Study Design: Controlled laboratory study. Methods: In 7 cadaveric specimens, the acetabular socket was prepared after the native LT was transected and the femoral head was removed. Seven separate tibialis anterior grafts were then prepared by suturing a running-locking No. 2 suture on each tail of the graft. Three specimens had fixation of the graft to the acetabulum using an adjustable cortical suspension suture button; the remaining 4 were fixed to the acetabulum using a knotless suture anchor. Specimens were then mounted onto a custom jig within a mechanical test frame to allow for the in-line pull of the graft fixation construct. After a preload of 5 N, each specimen was loaded to failure at 0.5 mm/s. Stiffness and load to failure were measured for each specimen construct. Results: Suture button fixation had a higher mean load to failure when compared with the knotless anchor fixation method (mean ± SD, 438.1 ± 114.3 vs 195.9 ± 50.0 N; P = .01). There was no significant difference in mean stiffness between the methods of fixation (24.5 ± 1.4 vs 26.5 ± 5.8 N/mm; P = .6). Conclusion: In this cadaveric study, the suture button fixation demonstrated greater load to failure than the knotless anchor fixation. Clinical Relevance: Results of this study can guide surgical decision making when selecting an acetabular fixation method for LT reconstruction.

Analysis of the Risk of Wear on Cemented and Uncemented Polyethylene Liners According to Different Variables in Hip Arthroplasty

Wear debris in total hip arthroplasty is one of the main causes of loosening and failure, and the optimal acetabular fixation for primary total hip arthroplasty is still controversial because there is no significant difference between cemented and uncemented types for long-term clinical and functional outcome. To assess and predict, from a theoretical viewpoint, the risk of wear with two types of polyethylene liners, cemented and uncemented, a simulation using the finite element (FE) method was carried out. The risk of wear was analyzed according to different variables: the polyethylene acetabular component’s position with respect to the center of rotation of the hip; the thickness of the polyethylene insert; the material of the femoral head; and the relationship of the cervical–diaphyseal morphology of the proximal end of the femur to the restoration of the femoral offset. In all 72 simulations studied, a difference was observed in favour of a cemented solution with respect to the risk of wear. With regard to the other variables, the acetabular fixation, the thickness of the polyethylene, and the acetabular component positioning were statistically significant. The highest values for the risk of wear corresponded to a smaller thickness (5.3 mm), and super-lateral positioning at 25 mm reached the highest value of the von Mises stress. According to our results, for the reconstruction of the acetabular side, a cemented insert with a thickness of at least 5 mm should be used at the center of rotation.

Cemented or uncemented acetabular fixation in combination with the Exeter Universal cemented stem

Aims To compare long-term survival of all-cemented and hybrid total hip arthroplasty (THA) using the Exeter Universal stem. Methods Details of 1,086 THAs performed between 1999 and 2005 using the Exeter stem and either a cemented (632) or uncemented acetabular component (454) were collected from local records and the New Zealand Joint Registry. A competing risks regression survival analysis was performed with death as the competing risk with adjustments made for age, sex, approach, and bearing. Results There were 61 revisions (9.7%; 0.82 revisions/100 observed component years, (OCYs)) in the all-cemented group and 18 (4.0%; 0.30/100 OCYs) in the hybrid group. The cumulative incidence of revision at 18 years was 12.1% for cemented and 5.2% for hybrids. There was a significantly greater risk of revision for all-cemented compared with hybrids (unadjusted sub-hazard ratio (SHR) 2.44; p = 0.001), and of revision for loosening, wear, or osteolysis (unadjusted SHR 3.77; p < 0.001). After adjustment, the increased risk of all-cause revision did not reach significance at age 70 years and above. The advantage for revision for loosening, wear, and osteolysis remained at all ages. Conclusion This study supports the use of uncemented acetabular fixation when used in combination with the Exeter stem with improved survivorship for revision for aseptic loosening, wear, and osteolysis at all ages and for all-cause revision in patients less than 70 years. Cite this article: Bone Joint J 2020;102-B(4):414–422

Trends in Total Hip Arthroplasty in Young Patients - Results from a Regional Register

Introduction In the United Kingdom, over 83,000 primary total hip arthroplasties (THAs) were performed last year, of which 20% are in patients under the age of 60 years. These patients generally have a longer life expectancy and a higher activity level than an older cohort, which may potentially translate to higher revision rates. Methods We reviewed our Trent regional arthroplasty register to assess current surgical practice in younger patients undergoing total hip arthroplasty. The results were compared to a previous study published in 2005. Results Between 2010 and 2012, 1,097 primary THAs were performed on patients aged 54 or less. There was an equal cohort of males to females with a mean age of 46 years of patients undergoing THA. Osteoarthritis was the commonest aetiology for patients having surgery. Reviewing the components used there were 32 different femoral and 30 different acetabular types along with 70 different combinations of components. There were 608 uncemented THAs, 313 hybrid THRs, 98 cemented THAs, 67 resurfacing arthroplasties and 11 reverse hybrid THAs. Discussion The majority of implants were uncemented in both femur and acetabulum with consultants performing most of the procedures. There is a clear preference for uncemented femoral and acetabular fixation in the younger patient, and the trend towards uncemented components has increased over the last 10 years amongst the same surgeons. There continues to be a wide variety of cup and stem usage along with many different combinations of components, with no consensus on the ideal combination.