The varus cemented femoral stem in total hip arthroplasty: Predictors, implications and The Femoral Access Ratio

Canal fill and radiographic comparison analysis of novel fully hydroxyapatite coated, variable triple-tapered geometry stems: one-year follow-up after direct anterior approach total hip arthroplasty

BACKGROUND

Optimal femoral stem alignment and femoral canal fill have been associated with improved osteointegration in patients undergoing cementless total hip arthroplasty (THA). Direct anterior approach (DAA) has become more popular among new surgeons, and the ability to achieve appropriate stem alignment and canal fill due to limited surgical exposure may pose added risks. To mitigate these concerns, several modern tissue sparing stem designs have been designed. This study aimed to compare implant canal fill and alignment between two of the leading DAA-friendly femoral stems available.

METHODS

This was a multi-center, retrospective study of patients who underwent DAA THA with either A (n = 149) or B stem (n = 85) between 2021 and 2023 and had a minimum one-year follow-up. Radiographic measures of proximal femoral morphology, including canal calcar ratio (CCR), Morphological Cortical Index (MCI), and Dorr Class (based on the CCR), as well as postoperative measures including femoral canal fill ratio (CFR), signs of osteointegration and stem alignment were analyzed and compared between stem types.

RESULTS

Proximal femoral morphology was similar between groups, as suggested by the CCR (p = 0.600), MCI (p = 0.489) and Dorr class distribution (p = 0.516). Patients who received stem A had improved CFR at the level of the lesser trochanter compared to patients who received stem B (0.73 vs. 0.70, respectively; p = 0.042), with similar CFR at the tip of the stem (0.76 vs. 0.77, p = 0.562). Similarly, there was a trend towards improving stem alignment for stem A patients (2.16o vs. 2.47o, p = 0.082). Spot weld formation was significantly higher in stem A group (59.7% vs. 37.6%, P = 0.001).

CONCLUSION

For patients with similar femoral morphology undergoing DAA THA, the stem A group demonstrated superior anatomical fit in the metaphyseal region, as evidenced by CFR, spot weld formation and implant positioning. Further longer follow up research is needed to elucidate these findings and their correlation to clinical outcomes.

Broach Only Total Hip Arthroplasty Using a Short, Uncemented, and Collarless, Fit-and-Fill Stem: Average 5-Year Follow-Up

BACKGROUND

Short femoral stem use in total hip arthroplasty can preserve bone stock and may diminish thigh pain. Tapered-wedge short stems are appealing, because reaming is not typically required as it is with classic "fit-and-fill" designed stems. This study aimed to evaluate the minimum 2-year clinical, radiographic, and clinical results of a short, uncemented, and collarless, fit-and-fill stem implanted using a broach-only technique.

METHODS

The clinical and radiographic results of a consecutive series of 505 cementless THAs were reviewed from 2 to 9 years postoperatively. The average age was 62 years (range, 32 to 91), and 54% of the patients were men. Dorr's class was 31% A, 64% B, and 5% C. All patients were followed for a minimum of 2 years. The average follow-up was 5.6 years (range, two to nine).

RESULTS

At the final follow-up, the average Harris hip and pain scores were 90 and 42, respectively. There were 82% of hips rated as pain-free. A single patient reported activity-related thigh pain. There were no cases of femoral aseptic loosening. At operation, 14% of stems were placed in more than five degrees of varus. An intraoperative femur fracture occurred in 13 hips (2.5%). There were two stems revised (one infection and one late femur fracture).

CONCLUSIONS

The theoretical advantages of using this collarless fit-and-fill stem may be offset by the tendency for varus placement and proximal femur fracture when using a broach-only technique. Nevertheless, the varus stems in this series remain well-ingrown and radiographically stable at an average 5-year follow-up.

Equivalent revision rates and patient reported outcomes with routine use of a short (125mm) cemented stem for total hip arthroplasty compared to a standard length (150mm) cemented stem. A two surgeon series of 1335 patients

BACKGROUND

Routine total hip arthroplasty (THA) using a short cemented stem as compared with a standard length cemented stem may have benefits in terms of stress distribution, bone preservation, stem subsidence and ease of revision surgery. Two senior arthroplasty surgeons transitioned their routine femoral implant from a standard 150 mm Exeter V40 cemented stem to a short 125 mm Exeter V40 cemented stem for all patients over the course of several years. We analysed revision rates, adjusted survival, and PROMS scores for patients who received a standard stem and a short stem in routine THA.

METHODS

All THAs performed by the two surgeons between January 2011 and December 2021 were included. All procedures were performed using either a 150 mm or 125 mm Exeter V40 stem. Demographic data, acetabular implant type, and outcome data including implant survival, reason for revision, and post-operative Oxford Hip Scores were obtained from the New Zealand Joint Registry (NZJR), and detailed survival analyses were performed. Primary outcome was revision for any reason. Reason for revision, including femoral or acetabular failure, and time to revision were also recorded.

RESULTS

1335 THAs were included. 516 using the 150 mm stem and 819 using the 125 mm stem. There were 4055.5 and 3227.8 component years analysed in the standard stem and short stem groups respectively due to a longer mean follow up in the 150 mm group. Patient reported outcomes were comparable across all groups. Revision rates were comparable between the standard 150 mm stem (0.44 revisions/100 component years) and the short 125 mm stem (0.56 revisions/100 component years) with no statistically significant difference found (p = 0.240).

CONCLUSION

Routine use of a short 125 mm stem had no statistically significant impact on revision rate or PROMS scores when compared to a standard 150 mm stem. There may be benefits to routine use of a short cemented femoral implant.

The compared study about femoral stem malalignment with or without the special curved rasp during DAA total hip arthroplasty

OBJECTIVE

To investigate whether the application of a curved rasp on the femoral side is effective in reducing the incidence of stem malalignment in total hip replacement with direct anterior approach (DAA-THA), followed by the analysis of the independent risk factors affecting stem malalignment.

METHODS

Retrospective analysis was carried out covering 160 patients undergoing DAA-THA from January 2019 to December 2021, with Tri-Lock (BPS, Depuy) stem applied in all 113 patients were screened according to inclusion and exclusion criteria. The data of gender, age, body mass index, preoperative diagnoses, Dorr classification, FAR ratio, pelvic morphology ratio, WOMAC scores, were analyzed to explore the independent factors influencing the malalignment of the femoral prosthesis implantation. Then data of patients were divided into group A and group B according to whether the curved rasp was taken during the operation. The chi-square test was performed to compare the incidence of femoral stem malalignment between the two groups.

RESULTS

There revealed two independent risk factors: BMI and FAR ratio that affected femoral stem malalignment. The increased BMI was associated with a higher probability of femoral stem malalignment (P<0.05), the probability of malalignment of femoral stem in FAR ratio<1 was 1.15 times higher than that in FAR>1(OR = 1.15, 95% CI: 1.03-1.28, P<0.05). Further grouping analysis showed that the incidence of femoral stem malalignment in patients with intraoperative application of curved rasp was 27%, while in patients without curved rasp, the incidence of femoral stem malalignment increased significantly to 48.7%(P<0.05). The placement angle of prosthesis in group A was significantly better than that in group B, especially mild femoral stem malalignment (0%) and severe femoral stem malalignment (2.70%), and the difference was statistically significant (P < 0.05). There found no significant difference in age, gander, intraoperative complications and last follow-up assessment of WOMAC scores between the two groups of patients.

CONCLUSIONS

In DAA-THA, BMI and FAR ratio act as the independent risk factors for femoral stem malalignment. Intraoperative use of a curved rasp significantly reduces the incidence of malalignment of the femoral stem.

Femoral Stem Cementation in Primary Total Hip Arthroplasty

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Femoral stem cementation has undergone considerable investigation since bone cement was first used in arthroplasty, leading to the evolution of modern femoral stem cementation techniques.

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Although there is a worldwide trend toward the use of cementless components, cemented femoral stems have shown superiority in some studies and have clear indications in specific populations.

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There is a large evidence base regarding cement properties, preparation, and application techniques that underlie current beliefs and practice, but considerable controversy still exists.

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Although the cementing process adds technical complexity to total hip arthroplasty, growing evidence supports its use in certain cohorts. As such, it is critical that orthopaedic surgeons and investigators have a thorough understanding of the fundamentals and evidence underlying modern cementation techniques.