The influence of stem alignment on the bone mineral density around the Polarstem following total hip arthroplasty

Impact of femoral stem alignment on periprosthetic bone density in THA: a study of the Avenir Complete stem

INTRODUCTION

Thigh pain, aseptic loosening, and failure after total hip arthroplasty has been reported. Therefore, this study examines the impact of femoral stem alignment on periprosthetic bone mineral density (BMD) in THA using the Avenir Complete cementless stem, focusing on the role of precise stem alignment in maintaining proximal femoral BMD.

MATERIALS AND METHODS

Consecutive patients who received the Avenir Complete stem via mini anterolateral approach in the supine position between March 2019 and March 2022 were included. Dual-energy X-ray absorptiometry was used to assess BMD changes, and computed tomography scans were used to evaluate stem alignment.

RESULTS

BMD was maintained in the distal femur, but showed a slight decrease in the proximal femur. A negative correlation was observed among varus malalignment, anteversion errors, and changes in BMD in the proximal femur.

CONCLUSIONS

The findings underscore the importance of accurate stem positioning in THA, particularly in avoiding varus malalignment and anteversion errors, as misalignment can adversely affect proximal femoral BMD and potentially lead to early stem loosening. This study enhances the understanding of the influence of the Avenir Complete stem on postoperative BMD, highlighting the need for precise alignment to optimize outcomes.

Total Hip Arthroplasty in Patients with Hip Osteoporosis: A Narrative Review

Osteoporosis and osteopenia can affect patients undergoing arthroplasty of the hip, which is typically recommended for patients with severe osteoarthritis or elderly patients with a femoral neck fracture. Preoperative screening for this type of bone loss could be helpful to patients and prevent poor outcomes due to the rate of underdiagnosis of osteoporosis, which can reach 73% in patients undergoing hip arthroplasty. Complications associated with low bone mineral density include periprosthetic fractures as well as an increased revision rate. Although the benefit of antiresorptive medications postoperatively has been demonstrated, when administered preoperatively, worse outcomes were reported compared to its non-usage. Surgical management is as important as pre-medication. According to general recommendations, cemented implants provide greater benefit in osteoporotic patients. However, when using cementless implants, ribbed stems, straight tapered stems, stems with medial calcar contact, and titanium-composed stems can be used to prevent periprosthetic loss of bone mineral density; however, they should not be placed in a varus position. These stems can also be coated with zoledronate and other products.

The assessment of canal flare index and proximal femoral bone density can improve stem selection for peri-prosthetic bone maintenance after total hip arthroplasty

INTRODUCTION

Bone maintenance after total hip arthroplasty (THA) is important for implant success. This study aimed to investigate the relationship between patient characteristics and periprosthetic bone maintenance after THA for better implant selection.

MATERIALS AND METHODS

This retrospective cohort study enrolled 112 consecutive patients who underwent THA using full hydroxyapatite (HA) compaction with short (n = 55) or short-tapered wedge (n = 61) stems. Periprosthetic bone mineral density (BMD) was compared between the two groups after propensity score matching, and the relationship between periprosthetic BMD changes and patient background was analyzed.

RESULTS

Both groups showed similar periprosthetic BMD changes after adjusting for patient background using propensity score matching. Canal flare index > 3.7 in patients that underwent THA using tapered-wedge stem (odds ratio (OR), 3.2; 95% confidence interval (CI), 1.3-7.9, p = 0.013) and baseline zone 1 BMD > 0.65 in patients that received with short HA compaction stems (OR, 430.0; 95% CI 1.3-1420, p = 0.040) were associated with proximal periprosthetic bone maintenance after THA.

CONCLUSION

Considering their predictive value, canal flare index and zone 1 BMD assessment might be useful strategies for implant selection during THA.

Bone mineral density around cementless short stems after reverse shoulder arthroplasty: changes over time and its relationship to stem positioning

Background

There are numerous reports of bone adaptation observed on plain radiography studies after the use of cementless short stems in reverse shoulder arthroplasty. However, reports on changes in bone mineral density (BMD) around the stem using dual-energy X-ray absorptiometry (DEXA) are prominently absent. In the present study, we measured BMD around the stem using DEXA and investigated changes over time from postoperative year 1 to year 2. Additionally, the relationship between BMD changes, filling ratio, and stem alignment was examined.

Methods

Forty-seven patients with short cementless stems who could be assessed via DEXA at 1-2 years postoperatively were included. After dividing the zones around the stem into 5, the BMD in each zone was measured, in addition to BMD changes and amount of change from postoperative year 1 to year 2. The relationship between filling ratio and stem alignment on postoperative plain radiography was assessed.

Results

A significant decrease in BMD in zone 3 was observed between postoperative year 1 and year 2 (P = .02). Regarding filling ratio and stem alignment, a negative correlation between valgus stem alignment and BMD change observed in zone 1 (r = -0.470, P < .01). In addition, stem valgus greater than 6° correlated with a significant decrease in BMD in zone 1. (P = .01). No significant differences were found in the other zones. Furthermore, there was no correlation between filling ratio and BMD change.

Conclusion

In reverse shoulder arthroplasty cementless short stems, changes that that occurred between postoperative year 1 to year 2 demonstrated a decrease in BMD in zone 3. In addition, a decrease in BMD in zone 1 was observed with a stem alignment of valgus 6° or higher, suggesting that stem alignment within valgus 6° is required to prevent a decrease in BMD.