Femoral Stem Subsidence and its Associated Factors after Cementless Bipolar Hemiarthroplasty in Geriatric Patients

The use of uncemented stems in femoral neck fractures in elderly patients: A comparative study of 671 cases

INTRODUCTION

The use of cemented stems in elderly patients is associated with the risk of intraoperative embolic complications. Uncemented stems eliminate this risk, but their use is controversial because of the risk of mechanical complications, with estimated subsidence between 3.6 and 30% and periprosthetic fractures between 2.1 and 11% at 6 weeks. A retrospective multicenter comparative study was conducted using a propensity score analysis to evaluate mechanical performances of uncemented stems in femoral neck fractures in elderly patients to (1) compare the risk of mechanical complications and (2) assess the use of metaphyseal-anchored stems for this indication.

HYPOTHESIS

There is no difference in the risk of mechanical complications, intraoperatively or postoperatively, between these stems.

MATERIALS AND METHODS

We conducted a multicenter retrospective comparative study including 358 uncemented and 313 cemented stems. The mean age was 84.5 years [83.9-85.1]. The inclusion criteria were patients 70 years and older and a follow-up of at least 6 weeks. The primary endpoint was a composite endpoint comprised of stem subsidence≥2mm or periprosthetic fracture (up to 3 months postoperatively). The secondary endpoints were infection, stem subsidence≥2mm, and operative time. These endpoints were analyzed using a propensity score to control confounding factors. A secondary analysis used the same endpoints to compare metaphyseal-anchored (short stems) versus Corail-like stems.

RESULTS

After adjusting for the propensity score, we found 11.17% mechanical complications in the uncemented group (n=40, 5.59% subsidence, and 5.59% fractures) versus 13.42% for the cemented group (n=42, 7.99% subsidence, and 5.43% fractures). There was no statistically significant difference between the 2 values (Odds Ratio [OR]=0.64 [95% Confidence Interval [CI]: 0.14-2.85] [p=0.7]). The mortality rate due to cement embolism was 1%. There was no difference in the rate of subsidence (OR=0.55 [95% CI: 0.02-12.5] [p=0.7]), periprosthetic fracture (OR=0.65 [95% CI: 0.13-3.12] [p=0.7]) or infection (OR=0.71 [95% CI: 0.32-1.55] [p=0.4]). However, the operative times were longer in the cemented group (p=0.03 for hemiarthroplasties [mean additional time 16minutes] and p=0.02 for total hip arthroplasties [mean additional time 22minutes]). No difference was observed between the metaphyseal-anchored (short stems) and Corail-like stems regarding operative time, rate of infection, and rate of stem subsidence or periprosthetic fractures.

DISCUSSION

This is one of the first studies to highlight cemented stem subsidence when used for femoral neck fractures in elderly patients. Using uncemented stems in this indication is still warranted, especially since they do not bring about more mechanical complications in the first few months. Metaphyseal-anchored short stems seem to give the same results as "standard" stems. However, these findings need to be assessed in the longer term.

LEVEL OF EVIDENCE

III; retrospective comparative study.

Does Lack of Initial Collar-Calcar Contact Influence Performance of Collared Cementless Femoral Stems?

Background

Initial stability of cementless stems is important to minimize the risk of subsidence, pain, and periprosthetic fracture after total hip arthroplasty (THA). Collared stems improve initial component stability when contacting the femoral calcar. Direct contact is not always achieved, and collared stem performance has not been studied in this context. We hypothesized that collared stems achieving direct contact would demonstrate reduced subsidence.

Methods

A single-surgeon retrospective study of 482 consecutive primary THAs implanted between February 2020 and May 2023 using collared cementless stems was performed. The 2 cohorts included stems with initial collar-calcar contact vs stems without. Subsidence was evaluated by comparing intraoperative fluoroscopy to postoperative 8-week radiographs. Binary logistic regression identified independent risk factors for subsidence. Chi-square tests were used for categorical variables and t-tests for continuous variables.

Results

Of stems, 63.9% achieved initial collar-calcar contact, while 36.1% did not. The rate (1.3% vs 19.0%; P < .001) and magnitude (0.02 mm, range 0-3 mm vs 0.35 mm, range 0-3 mm; P < .001) of subsidence were significantly higher among stems without initial contact. Stems without initial collar-calcar contact (P < .001) and male gender (P = .007) were independent risk factors for subsidence. Two patients with initial contact had nondisplaced calcar cracks and <3 mm of subsidence at 4 weeks, which healed with protected weight-bearing. Stem survivorship was 100% in both groups, with all achieving osteointegration and none needing revision.

Conclusions

Excellent performance of collared cementless stems was observed at 8 weeks after primary THA. Initial collar-calcar contact lowered the risk and magnitude of minor subsidence but did not affect survivorship or fracture risk.

Level of Evidence

Level III.

Incidence and Predictors of Subsidence Using Modular, Tapered, Fluted Titanium Femoral Stems in Aseptic Revision Total Hip Arthroplasty

BACKGROUND

Tapered, fluted titanium (TFT) femoral stems have become the gold standard in revision total hip arthroplasty (rTHA). However, there is a paucity of data on TFT stem subsidence rates following aseptic rTHA. Subsidence can lead to instability, mechanical failure, leg-length discrepancy, and may require revision surgery. This study evaluated the incidences and predictors of TFT subsidence in aseptic rTHA.

METHODS

A total of 102 TFT femoral stems of 4 designs were retrospectively reviewed. Stem subsidence was measured on digital radiographs taken immediately after surgery and at standard clinical follow-up. Patient characteristics, risk factors for subsidence, revision etiologies, and implant characteristics were recorded. Patient-reported outcome measures were also evaluated for a subset of cases.

RESULTS

Overall, 12% of stems subsided >1 cm, and subsidence was minimal (<3 mm) in ≥64% of cases. From immediate postoperative to 1-month radiographic follow-up, 79% of stems subsided a mean of 2.9 mm (range, 0.1 to 12 mm). Beyond 1 month, subsidence was minimal for ≥77% of cases. In multivariate analyses, women and less femoral implant canal fill were associated with greater subsidence (P ≤ .034). The TFT stem design was not associated with early subsidence (P = .816). There were no modular junction fractures. There were 2 fractures and 2 subsidence-related revisions for aseptic loosening that occurred postoperatively.

CONCLUSIONS

The amount of subsidence in TFT stems was low and was detectable in the early (less than 1 year) postoperative period. Maximizing TFT stem fill within the femoral canal appears to reduce the risk of subsidence without increasing femoral fracture rates and should be the goal with implantation of these devices.

LEVEL OF EVIDENCE

IV-Case Series, No Control Group.

Radiological Comparison of Canal Fill between Collared and Non-Collared Femoral Stems: A Two-Year Follow-Up after Total Hip Arthroplasty

Collared femoral stems in total hip arthroplasty (THA) offer reduced subsidence and periprosthetic fractures but raise concerns about fit accuracy and stem sizing. This study compares collared and non-collared stems to assess the stem-canal fill ratio (CFR) and fixation indicators, aiming to guide implant selection and enhance THA outcomes. This retrospective single-center study examined primary THA patients who received Corail cementless stems between August 2015 and October 2020, with a minimum of two years of radiological follow-up. The study compared preoperative bone quality assessments, including the Dorr classification, the canal flare index (CFI), the morphological cortical index (MCI), and the canal bone ratio (CBR), as well as postoperative radiographic evaluations, such as the CFR and component fixation, between patients who received a collared or a non-collared femoral stem. The study analyzed 202 THAs, with 103 in the collared cohort and 99 in the non-collared cohort. Patients' demographics showed differences in age (p = 0.02) and ASA classification (p = 0.01) but similar preoperative bone quality between groups, as suggested by the Dorr classification (p = 0.15), CFI (p = 0.12), MCI (p = 0.26), and CBR (p = 0.50). At the two-year follow-up, femoral stem CFRs (p = 0.59 and p = 0.27) were comparable between collared and non-collared cohorts. Subsidence rates were almost doubled for non-collared patients (19.2 vs. 11.7%, p = 0.17), however, not to a level of clinical significance. The findings of this study show that both collared and non-collared Corail stems produce comparable outcomes in terms of the CFR and radiographic indicators for stem fixation. These findings reduce concerns about stem under-sizing and micro-motion in collared stems. While this study provides insights into the collar design debate in THA, further research remains necessary.

Demographic characteristics influencing the stem subsidence in total hip arthroplasty: an imaging study

INTRODUCTION

The present study evaluated whether patient demographic characteristics influence the subsidence of the stem in total hip arthroplasty (THA). The following characteristics were evaluated: age, height, weight, and sex. The association between the time elapsed from the THA implantation and the amount of stem subsidence was also investigated.

METHODS

The records of patients who underwent THA in the period between 2016 and 2023 were accessed. All patients underwent two-staged bilateral THA using cementless DePuy collarless Corail (DePuy Synthes, Raynham, MA, USA) stems. The following parameters were measured and compared to assess stem subsidence: distance from the proximal femur at the stem bone interface and the medial apex of the regular triangle built within the trochanter minor (point A); distance from the medial apex of the regular triangle built within the trochanter minor and the distal portion of the femoral stem (point B).

RESULTS

Overall, 294 patients were included. 62% (182 of 294 patients) were women. 45% (134 of 296 THAs) were on the right side. The mean age was 64.9 ± 10.4 years. The mean BMI was 28.3 ± 5.1 kg/m2. The mean length of the follow-up was 14.4 ± 11.0 months. The mean subsidence in point A was 2.1 mm (P < 0.0001), and that in point B was 3.1 mm (P < 0.0001). There was evidence of a weak positive association between patient weight (P < 0.0001), age (P = 0.03), follow-up (P = 0.002) and the amount of stem subsidence. Patient height did not demonstrate any association with the amount of stem subsidence (P = 0.07). There was no difference in stem subsidence between women and men (P = 0.9).

CONCLUSION

Stem subsidence in THA using cementless DePuy collarless Corail implants is approximately 2.6 mm after 14.4 months. Greater patient weight, age, and longer time elapsed from THA implantation were associated with greater stem subsidence. Patient height and sex did not demonstrate any influence on the amount of stem subsidence. These results must be considered in light of the limitations of the present study.

High grade femoral stem subsidence in uncemented hip hemiarthroplasty - A radiographic analysis and an early prediction while treating femoral neck fractures

PURPOSE

Femoral component subsidence is a known risk factor affecting almost all hip replacements using a collarless, cement-less stems. High grade subsidence >5mm is functionally limiting to the patient. Early analysis and prediction of this complication on the immediate post-operative radiographs will help surgeons to opt for alternative solutions to mitigate this complication.

METHODS

A retrospective study including 116 patients, who underwent cement-less bipolar hemi-arthroplasties treated from 2020-2022 were included in the study. Body Mass Index (BMI) and pre-operative American Society Anesthesiologist (ASA) score was retrieved from the medical records. Post operative radiographs on postoperative day two, at four weeks and at eight weeks were evaluated. Dorr's score, initial subsidence ratio (ISR) , stem angulation, proximal stem-canal fit (PSCF) ratio, distal stem-canal fit (DSCF) ratio, medial flare modifier (MFM) were recorded.

RESULTS

A total of 18 patients showed subsidence over 5mm on radiographs evaluated at four weeks. The mean high-grade stem subsidence was 13.5mm +/- 2.67. Evaluating their respective postoperative day two radiographs- ISR was >1 in 16 out of 18 patients (89%), PSCF ratio <0.75 in 83% and DSCF ratio <0.5 in 78% patients. All these patients had a neutral/negative MFM. BMI >25 (p<0.05) and ASA >3 (p<0.001) correlated with a higher degree of stem subsidence.

CONCLUSION

A lower BMI and ASA score accompanied by a positive MFM were protective factors against femoral stem subsidence. A higher ISR along with a PSCF ratio <0.75 and DSCF ratio <0.5, were highly predictive of stem subsidence over 5 mm.