Subsidence and perioperative periprosthetic fractures using collarless hydroxyapatite-coated stem for displaced femoral neck fractures according to Dorr type

What features of stem increase the risk of intraoperative femoral fracture during cementless primary hip arthroplasty?

INTRODUCTION

Cementless fixation has become increasingly popular in hip arthroplasty due to its shorter operation time, easier technique, biologic fixation, and avoidance of bone cement implantation syndrome compared to cemented fixation. However, intraoperative periprosthetic femoral fracture (IOPFx) is a disconcerting complication during cementless hip arthroplasty. Our purpose was to identify the features of cementless stem that increase the risk of IOPFx during primary hip arthroplasty.

MATERIALS AND METHODS

We retrospectively reviewed all 4806 hip arthroplasties that was performed in a single institution from May 2003 to December 2020. Age at the index arthroplasty, sex, body mass index, physical status, ambulatory function, side of the operation, operational history, cause of the index arthroplasty, type of arthroplasty, surgical approach, surgeon, implant information, and events during the operation were investigated. The shoulder geometry and length of stem were also reviewed. The event of interest was narrowed down to IOPFx among various records of intraoperative events.

RESULTS

We found IOPFx of 2.6% among all the hips operated with cementless stem. In the multivariable analysis, female (OR = 1.52), childhood hip disease (OR = 2.30), stove-pipe femur (OR = 2.43), combined approach (OR = 2.60), and standard length of stem (OR = 1.59) were found to be significant risk factors of IOPFx.

CONCLUSIONS

In conclusion, a stem with a standard length is significantly associated with risk of IOPFx compared to a shortened stem. These findings highlight the importance of careful consideration in terms of the risk of IOPFx when standard length cementless stem is chosen.

Effects of Cerclage Cabling on Preventing Periprosthetic Femoral Fractures When Using Cementless Stems for Unstable Femoral Neck Fractures

BACKGROUND

Periprosthetic femoral fractures (PFFs) are serious complications in hip arthroplasty for femoral neck fractures. The rates of intraoperative (iPFFs) and postoperative PFFs (pPFFs) are higher in cementless stem cases than in cemented cases. This study aimed to investigate the effects of cerclage cabling on PFF prevention in cementless arthroplasty for femoral neck fractures.

METHODS

This retrospective study included 329 consecutive patients who underwent hip arthroplasty using a cementless stem for femoral neck fractures. A total of 159 and 170 patients were in the non-cabling and cabling groups, respectively. Patient characteristics were comparable in both groups. The PFF occurrence (iPFF and pPFF) rates, reoperation rates, operative time, and blood loss volume were compared between the groups.

RESULTS

The iPFF rate was significantly higher in the noncabling group (6.3%) than in the cabling group (0%, P < .001). The rate of pPFF was significantly higher in the non-cabling group (5.1%) than in the cabling group (0.6%; P = .016). All patients in the non-cabling group required reoperation (5.1%), whereas the patient in the cabling group was an ambulatory case and required no reoperation (0%, P = .003). No significant difference in either operative time or blood loss volume was observed between the non-cabling (50 minutes, 133 mL) and cabling (52 minutes, P = .244; 149 mL, P = .212, respectively) groups.

CONCLUSIONS

When a cementless stem is used to treat unstable femoral neck fractures, cerclage cabling effectively prevents iPPF and pPPF without increasing surgical time or blood loss volume.

Small design modifications can improve the primary stability of a fully coated tapered wedge hip stem

Increasing the stem size during surgery is associated with a higher incidence of intraoperative periprosthetic fractures in cementless total hip arthroplasty with fully coated tapered wedge stems, especially in femurs of Dorr type A. If in contrast a stem is implanted and sufficient primary stability is not achieved, such preventing successful osseointegration due to increased micromotions, it may also fail, especially if the stem is undersized. Stem loosening or periprosthetic fractures due to stem subsidence can be the consequence. The adaptation of an established stem design to femurs of Dorr type A by design modifications, which increase the stem width proximally combined with a smaller stem tip and an overall shorter stem, might reduce the risk of distal locking of a proximally inadequately fixed stem and provide increased stability. The aim of this study was to investigate whether such a modified stem design provides improved primary stability without increasing the periprosthetic fracture risk compared to the established stem design. The established (Corail, DePuy Synthes, Warsaw, IN, US) and modified stem designs (Emphasys, DePuy Synthes, Warsaw, IN, US) were implanted in cadaveric femur pairs (n = 6 pairs) using the respective instruments. Broaching and implantation forces were recorded and the contact areas between the prepared cavity and the stem determined. Implanted stems were subjected to two different cyclic loading conditions according to ISO 7206-4 using a material testing machine (1 Hz, 600 cycles @ 80 to 800 N, 600 cycles @ 80 to 1600 N). Translational and rotational relative motions between stem and femur were recorded using digital image correlation. Broaching and implantation forces for the modified stem were up to 40% higher (p = 0.024), achieving a 23% larger contact area between stem and bone (R2 = 0.694, p = 0.039) resulting in a four times lower subsidence during loading (p = 0.028). The slight design modifications showed the desired effect in this in-vitro study resulting in a higher primary stability suggesting a reduced risk of loosening. The higher forces required during the preparation of the cavity with the new broaches and during implantation of the stem could bare an increased risk for intraoperative periprosthetic fractures, which did not occur in this 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.

Primary Stability of Collared and Collarless Cementless Femoral Stems - A Finite Element Analysis Study

Background

Primary stability of the femoral stem is important for the long-term results of cementless total hip arthroplasty. Cementless collared stems have been known to have higher stability than collarless stems when there is a contact between the collar and the calcar. The purpose of this study was to compare the stabilities of collared stem and collarless stem in 2 loading conditions: 1) flat walking and 2) stair climbing.

Methods

We constructed 3 finite element models. In the first model, the collar had contact with the calcar. The second model had a 1 mm gap between the calcar and the collar. The third model was constructed with a collarless stem. The proximal femur around the stem was divided into 3 zones: the upper zone (Gruen zones 1 and 7), the middle zone (Gruen zones 2 and 6), and the lower zone (Gruen zones 3 and 5). The micromotion at the stem/bone interface was measured at each zone of the 3 models under the 2 loading conditions.

Results

The results showed that collared stems were more stable when the collar was in contact with the calcar than when a gap was left between the collar and the calcar. In particular, collar contact was highly effective in suppressing the micromotion proximal to the stem.

Conclusions

Compared to the collarless stem, the collared stem had comparable stability when there was a gap at the collar and calcar interface and higher stability when there was contact between the collar and the calcar.

Cementless total hip arthroplasty with anatomic-shaped implants. Does the minimal invasive anterolateral technique influence the stem position or subsidence in contrast to the standard lateral approach?

INTRODUCTION

Using cementless stems in total hip arthroplasty (THA) has revealed variable results. The risk for early aseptic loosening has been associated to certain surgical approaches and implant designs. This study determines misalignment of collared/collarless stems and the rate of subsidence using the anterolateral approach (ALA) compared to implantations via the direct lateral approach (DLA).

MATERIALS AND METHODS

One hundred consecutive patients underwent primary unilateral THA using the minimal invasive ALA in the lateral decubitus position and were compared to another cohort of 100 patients, treated trough the DLA. Clinical results were noted preoperatively and after 1 year using the WOMAC score. The radiographic evaluation included the stem alignment and subsidence.

RESULTS

Overall, all patients improved in WOMAC from 48.9 points (± 11.4; 21.0-82.0) to 3.1 (± 3.2; 0.0-22.0) (p < 0.001). For DLA and ALA, the stem was placed on average 2.5° in varus to the femoral axis. The mean alignment was about 0.5° more valgus for collarless stems. The mean subsidence in the DLA group was about 0.3 mm higher compared to the ALA group. With collarless implants, the subsidence was about 1.0 mm higher compared to collared implants (p < 0.05), especially in patients with Dorr type B femurs.

CONCLUSIONS

Changing from the DLA to the minimal invasive ALA did not significantly affect the implant position. Misalignment and a potential risk for early aseptic loosening could not be seen. The use of a collared cementless stem seems safe and is likely to prevent a relevant subsidence, even more so in Dorr type B femurs.

LEVEL OF EVIDENCE

III.

Tapered wedge stems decrease early postoperative subsidence following cementless total hip arthroplasty in Dorr type C femurs compared to fit-and-fill stems

Background

To compare the degree of stem subsidence between two different femoral component designs and to determine the risk factors associated with stem subsidence after cementless total hip arthroplasty (THA) in Dorr type C femurs.

Methods

We retrospectively reviewed 104 consecutive hips in 100 patients with Dorr type C proximal femoral morphology who underwent primary cementless THA using a fit-and-fill stem or a tapered wedge femoral stem at our institution between January 2012 and June 2021. A fit-and-fill stem was used in 55 hips and a tapered wedge stem was used in 49 hips. Radiologically, the distance between the apex of the major trochanter and the stem shoulder were measured at three different time points (immediately [0W], one week [1W], and six weeks [6W] after surgery) and the degrees of stem subsidence were assessed by comparing the distance between 0 and 1W, 1W and 6W, and 0W and 6W, respectively.

Results

The mean degree of stem subsidence (0W vs. 1W) was 0.24 mm (standard deviation [SD] 0.36) in the fit-and-fill stem group, and 0.23 mm (SD 0.41) in the tapered wedge stem group. There was no significant difference between the two groups (P = 0.4862). However, the mean degrees of subsidence were significantly higher in the fit-and-fill stem group (1W vs. 6W, 0.38 mm [SD 0.68]; 0W vs. 6W, 0.65 mm [SD 0.87]) than in the tapered wedge stem group (1W vs. 6W, 0.16 mm [SD 0.32]; 0W vs. 6W, 0.24 mm [SD 0.38]) (P < 0.05 for both). In addition, the rates of > 3 mm subsidence (in which instability can be observed) were 18.2% (10 of 55 hips) and 2.0% (1 of 49 hips), respectively. There was also a significant difference between the two stems (P = 0.0091). Multivariate analysis demonstrated that fit-and-fill stem was a risk factor for > 3 mm subsidence after THA in Dorr type C femurs (P = 0.0050).

Conclusion

Our findings suggest that the tapered wedge stem is more suitable for Dorr type C femurs than the fit-and-fill stem to avoid early postoperative subsidence in cementless THA.

Use of a Plasma-Sprayed Titanium-Hydroxyapatite Femoral Stem in Hip Arthroplasty in Patients Older than 70 Years. Is Cementless Fixation a Reliable Option in the Elderly?

Background: Although cementless implants are increasing in popularity, the use of cementless femoral stems for total hip arthroplasty (THA) and hip hemiarthroplasty (HH) in elderly patients remains controversial. The aim of this study was to report the outcomes of a cementless stem used in a large multicentric cohort of elderly patients receiving elective THA and HH for displaced femoral neck fracture. Methods: A total of 293 patients (301 hips) aged 70 years or older (mean age, 78 years; range, 70–93) who received the same cementless plasma-sprayed porous titanium–hydroxyapatite stem were retrospectively evaluated after primary THA and HH to investigate stem survival, complications, and clinical and radiographic results. Results: Cumulative stem survival was 98.5% (95% CI, 96.4–99.4%; 91 hips at risks) with revision due to any reason as the end-point at 10-year follow-up (mean 8.6 years, range 4–12). No stem was revised due to aseptic loosening. The mean Forgotten Joint Score was 98.7. Radiographically, the implants showed complete osseointegration, with slight stress-shieling signs in less than 10% of the hips. Conclusion: The use of cementless stems was proven to be a reliable and versatile option even in elderly patients for elective THA and HH for femoral neck fracture.

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

Introduction

Early femoral stem subsidence has been a concern as a predictor of the beginning of implant loosening, especially on cementless hip arthroplasty implants. This study aimed to determine the factors that affect femoral stem subsidence and outcome following hemiarthroplasty in the geriatric population.

Materials and Methods

This is a retrospective study of 179 patients who underwent cementless bipolar hemiarthroplasty during the 2011-2019 period at an orthopaedic and traumatology hospital. Data on the patient's demography, pre-operative American Society Anaesthesiologist (ASA) score, body mass index (BMI), canal flare index (CFI), Dorr classification, and stem alignment were obtained. The primary outcomes were post-operative femoral stem subsidence, post-operative pain, and functional outcome using Harris Hip Score (HHS). Statistical analysis was conducted to identify risk factors associated with the primary outcome.

Results

The mean femoral stem subsidence was 2.16 ±3.4 mm. The mean post-operative Visual Analog Score (VAS) on follow-up was 1.38 ± 1. Mean HHS on follow-up was 85.28±10.3. American Society Anaesthesiologist score 3 (p = 0.011, OR = 2.77) and varus alignment (p=0.039, OR = 6.963) were related to worse stem subsidence. Otherwise, neutral alignment (p = 0.045 and OR = 0.405) gave protection against femoral stem subsidence. The female gender (p = 0.014, OR 2.53) was associated with postoperative pain onset. Neutral alignment had significant relationship with functional outcomes (p = 0.01; OR 0.33).

Conclusion

A higher ASA score and varus stem alignment were related to a higher risk of femoral stem subsidence. Meanwhile, neutral stem alignment had a protective effect on the femoral stem subsidence and outcome.

The effect of femoral stem collar on implant migration and clinical outcomes following direct anterior approach total hip arthroplasty

AIMS

The direct anterior (DA) approach has been associated with rapid patient recovery after total hip arthroplasty (THA) but may be associated with more frequent femoral complications including implant loosening. The objective of this study was to determine whether the addition of a collar to the femoral stem affects implant migration, patient activity, and patient function following primary THA using the DA approach.

METHODS

Patients were randomized to either a collared (n = 23) or collarless (n = 26) cementless femoral stem implanted using the DA approach. Canal fill ratio (CFR) was measured on the first postoperative radiographs. Patients underwent a supine radiostereometric analysis (RSA) exam postoperatively on the day of surgery and at two, four, six, 12, 26, and 52 weeks postoperatively. Patient-reported outcome measures (Western Ontario and McMaster Universities Osteoarthritis (WOMAC) Index, the 12-item Short Form Health Survey Mental and Physical Score, and University of California, Los Angeles (UCLA) Activity Score) were measured preoperatively and at each post-surgery clinic visit. Activity and function were also measured as the weekly average step count recorded by an activity tracker, and an instrumented timed up-and-go (TUG) test in clinic, respectively.

RESULTS

Comparing the RSA between the day of surgery baseline exam to two weeks postoperatively, subsidence was significantly lower (mean difference 2.23 mm (SD 0.71), p = 0.023) with collared stems, though these patients had a greater CFR (p = 0.048). There was no difference (p = 0.426) in subsidence between stems from a two-week baseline through to one year postoperatively. There were no clinically relevant differences in PROMs; and there was no difference in the change in activity (p = 0.078) or the change in functional capacity (p = 0.664) between the collared stem group and the collarless stem group at any timepoint.

CONCLUSION

Presence of a collar on the femoral stem resulted in reduced subsidence during the first two postoperative weeks following primary THA using the DA approach. However, the clinical implications are unclear, and larger studies examining patient activity and outcomes are required. Cite this article: Bone Joint J 2020;102-B(12):1654-1661.