Excessive polyethylene wear and acetabular bone defects from standard use of a hooded acetabular insert in total hip arthroplasty

Evaluation of the reproducibility of preoperative three-dimensional computed tomography planning for posterolateral approach total hip arthroplasty

The anteversion of the stem is occasionally intentionally changed by the surgeon for patients with smaller femoral neck anteversion during total hip arthroplasty (THA). However, the reproducibility of preoperative planning with increasing anteversion has been rarely assessed. The present study investigated it using two types of stems. This retrospective study included patients who underwent primary posterolateral THA using taper-wedge (TS group; 73 hips) and anatomical (AS group; 70 hips) stems. Characteristics of sex and age were matched in the two groups by propensity score matching. In both groups, the relationship between the preoperative three-dimensional planning and postoperative stem position, and the relationship between postoperative stem position and femoral neck anteversion (FNA) were evaluated. In the TS group, there were no significant differences in average stem anteversion (SA) between preoperative planning and postoperative placement (36.1° ± 7.0° and 36.6° ± 11.1°, respectively: p = 0.651). The absolute error of SA was 8.1° ± 6.4°. In the AS group, the postoperative SA was significantly smaller than the preoperative planning SA (22.7° ± 11.6° and 30.0° ± 9.3°, respectively: p < 0.001). The absolute error of SA was 9.0° ± 5.8°. The postoperative SA was significantly larger than the FNA in the TS group (36.6° ± 11.1° and 26.3° ± 10.9°, respectively: p < 0.001). However, no significant differences between the two were observed in the AS group (23.7° ± 10.1° and 22.7° ± 11.6°, respectively: p = 0.253). The preoperative planning of intentional increasing anteversion did not show high reproducibility with taper-wedge and anatomical stems. The anatomical stem was placed according to the femoral medullary canal regardless of preoperative planning with increased SA.

[Standard and special liner in primary hip arthroplasty : Current study and survey results from the German Arthroplasty Registry (EPRD)]

BACKGROUND

Instability constitutes the main reason for revision hip arthroplasties. Modified polyethylene liners are designed to improve the stability of a hip replacement. In July 2022 The Bone & Joint Journal published a study with data of the German Arthroplasty Registry (EPRD). The study investigated mechanical failure of standard and modified liner designs in primary, cementless total hip arthroplasty. Following the study, the EPRD conducted a survey of German clinics to research the utilization of lipped liners in primary total hip replacement.

METHODS

The liner study included 151,096 primary, elective, cementless total hip arthroplasties. Data from November 2012 to November 2020 were obtained from the EPRD. Standard polyethylene liners were compared with lipped, angulated, offset and angulated/offset inlays. Cumulative incidences for endpoint revision due to mechanical complication were calculated with a competing risk analysis. The influence of other variables was investigated with a multivariate Cox regression. In the following online survey, 237 out of 789 hospitals completed a form.

RESULTS AND CONCLUSION

In our analysis, only offset liners were, compared to standard liners, associated with a reduced risk of mechanical failure in a short to medium follow up. However, the resultant joint reaction force is increased with offset liners due to the lateralization of the hip center of rotation. Thus, the long-term performance of offset liners needs to be observed. Our survey indicated that lipped liners were implanted more often if the posterior approach was used. Moreover, lipped liners were mostly positioned with the elevated rim in the biomechanically less optimal posterior-superior quadrant. To improve stability it is suggested to position the elevated rim in the posterior-inferior quadrant.

Modified acetabular component liner designs are not superior to standard liners at reducing the risk of revision : an analysis of 151,096 cementless total hip arthroplasties from the German Arthroplasty Registry

AIMS

Registry studies on modified acetabular polyethylene (PE) liner designs are limited. We investigated the influence of standard and modified PE acetabular liner designs on the revision rate for mechanical complications in primary cementless total hip arthroplasty (THA).

METHODS

We analyzed 151,096 primary cementless THAs from the German Arthroplasty Registry (EPRD) between November 2012 and November 2020. Cumulative incidence of revision for mechanical complications for standard and four modified PE liners (lipped, offset, angulated/offset, and angulated) was determined using competing risk analysis at one and seven years. Confounders were investigated with a Cox proportional-hazards model.

RESULTS

Median follow-up was 868 days (interquartile range 418 to 1,364). The offset liner design reduced the risk of revision (hazard ratio (HR) 0.68 (95% confidence interval (CI) 0.50 to 0.92)), while the angulated/offset liner increased the risk of revision for mechanical failure (HR 1.81 (95% CI 1.38 to 2.36)). The cumulative incidence of revision was lowest for the offset liner at one and seven years (1.0% (95% CI 0.7 to 1.3) and 1.8% (95% CI 1.0 to 3.0)). No difference was found between standard, lipped, and angulated liner designs. Higher age at index primary THA and an Elixhauser Comorbidity Index greater than 0 increased the revision risk in the first year after surgery. Implantation of a higher proportion of a single design of liner in a hospital reduced revision risk slightly but significantly (p = 0.001).

CONCLUSION

The use of standard acetabular component liners remains a good choice in primary uncemented THA, as most modified liner designs were not associated with a reduced risk of revision for mechanical failure. Offset liner designs were found to be beneficial and angulated/offset liner designs were associated with higher risks of revision. Cite this article: Bone Joint J 2022;104-B(7):801-810.

Does difference in stem design affect accuracy of stem alignment in total hip arthroplasty with a CT-based navigation system?

The efficacy of a computed tomography (CT)-based navigation system to accurately position the stem for intended alignment is unclear. In addition, the influence of stem design on the accuracy of insertion is unknown. We therefore retrospectively compared the accuracy and precision for the intended alignment of two different designs of femoral stem which were implanted with or without the navigation system. Forty-nine total hip arthroplasties (THAs) using a tapered wedge stem and 91 THAs using an anatomic stem were evaluated for the navigation group. Thirty-three THAs using the tapered wedge stem and 15 THAs using the anatomic stem were controls for the non-navigation group. Differences between postoperative measurement and preoperative planning were compared among the groups. In the navigation groups, accuracy (mean absolute difference) and precision (95% limits of agreement) of stem anteversion were 4.3° and ± 10.1° in the tapered wedge stem and 3.1° and ± 6.9° in the anatomic stem. In the non-navigation groups, these were 6.0° and ± 15.2° and 4.8° and ± 12.4°, respectively. The accuracy and precision in the navigation groups were significantly superior to those in the non-navigation group, and those in the anatomic stem group were significantly superior to those in the tapered wedge group. Using the CT-based navigation system, the accuracy and precision for intended stem anteversion were improved. When compared under guidance of navigation system, the accuracy and precision for intended stem anteversion in the anatomic stem were superior to those in the tapered wedge stem.

Are Hooded, Crosslinked Polyethylene Liners Associated with a Reduced Risk of Revision After THA?

BACKGROUND

Hooded acetabular liners and head sizes ≥ 32 mm have both shown to have a beneficial effect on the revision rate for dislocation in THA. Experience with noncrosslinked polyethylene (nonXLPE) raised concerns regarding the risk of impingement damage, loosening, and osteolysis with hooded liners; however, the evidence for this in crosslinked polyethylene (XLPE) is inconclusive. The interaction between different femoral head sizes and hooded liners is not well understood, and it is unclear whether hooded XLPE liners have a beneficial effect on overall long-term survivorship.

QUESTIONS/PURPOSES

We analyzed a large national joint registry to ask: (1) Is the use of hooded XLPE liners associated with a reduced revision rate for dislocation compared with nonhooded liners? (2) Is there a difference in the revision rate for aseptic loosening/osteolysis? (3) Is head size associated with any difference in the revision rate between hooded and nonhooded liners?

METHODS

The Australian Orthopaedic Association National Joint Replacement Registry longitudinally maintains data on all primary and revision joint arthroplasties with nearly 100% capture. We analyzed all conventional primary THAs performed from registry inception in September 1999 until December 31, 2016 in patients with a diagnosis of osteoarthritis who had nonhooded or hooded XLPE bearings in a cementless acetabular shell. The study group included 192,659 THA procedures with XLPE liners, of which 67,904 were nonhooded and 124,755 were hooded. The mean age of patients receiving nonhooded liners was 70 years (range, 11-100 years); 44% were males. This was similar to the patients with hooded liners, who had a mean age of 70 years (range, 16-100 years); 45% were males. The main outcome measure was the cumulative percent revision at 15 years of the THA using Kaplan-Meier estimates of survivorship. We examined reasons for revision and and performed multivariable analysis to control for the confounding factors of three head size groups (< 32mm, 32mm, and > 32mm) and for the method of femoral fixation.

RESULTS

There was a higher revision rate for dislocation for patients with nonhooded liners at all times to 15 years (HR, 1.31; 95% CI, 1.17-1.47; p < 0.001). There was a higher revision rate for the diagnosis of aseptic loosening/osteolysis with patients with nonhooded liners compared with hooded liners (HR, 1.19; 95% CI, 1.05-1.34; p = 0.006). Head sizes of 32 mm or larger were independently associated with a lower comparative revision rate between hooded and nonhooded liners, but this was not apparent for head sizes smaller than 32 mm. It appeared that the main driver of the finding in larger heads was a reduced dislocation risk with hooded liners for 32 mm heads (HR, 1.50; 95% CI, 1.23-1.80; p < 0.001) and for heads larger than 32 mm (HR, 1.50; 95% CI, 1.20-1.89; p < 0.001).

CONCLUSIONS

Prior research has suggested that hooded acetabular liners may be associated with impingement, loosening, and osteolysis; however, in this large, registry-based report we found that XLPE hooded liners are not associated with an increased revision rate for aseptic loosening/osteolysis. Although there are many potential confounding variables in this registry analysis, if anything, surgeons using larger femoral heads and hooded liners likely did so in patients with a higher perceived dislocation risk. Patients with larger heads and XLPE hooded liners were, however, less likely to experience revision for dislocation. These liners therefore appear reasonable to use in primary THA at the surgeon's discretion.

LEVEL OF EVIDENCE

Level III, therapeutic study.