An Update on Cementless Femoral Fixation in Total Hip Arthroplasty

Early Outcomes Following Total Hip Arthroplasty With a Newly Designed, Collared Triple-Tapered Cementless Femoral Stem

BACKGROUND

Cementless femoral fixation in total hip arthroplasty (THA) is the most frequently utilized technique in the United States due to the efficacy of biologic fixation and reduced intraoperative times compared with cemented fixation, but has been associated with complications, including periprosthetic fracture and loosening. A recently introduced collared triple-tapered cementless stem has been engineered to address and mitigate these adverse events, but its safety remains unproven. The purpose of this study was to report early complications and causes of failure of this stem and to report patient satisfaction and function.

METHODS

A retrospective review of patients who underwent primary THA using this device at a single institution from April 2022 to January 2024 was conducted. A total of 443 cases were performed that met the inclusion criteria. Patient demographics, including age, sex, American Society of Anesthesiologists score, and comorbidities, were collected. The primary outcome of interest was early complications (within 90 days) requiring readmission or revision surgical intervention. Patient-reported outcome measures (PROMs) such as the Veterans Rand 12 Item Health Survey (both physical and mental components), Hip Dysfunction and Osteoarthritis Outcome Score for Joint Replacement, and the Harris Hip Score were also recorded and analyzed.

RESULTS

A total of six patients (1.4%) required reoperation or readmission following their THA. There was one Vancouver B2 periprosthetic fracture sustained after a fall at physical therapy (0.2%) and one acute periprosthetic infection (0.2%) that required reoperation. There were four patients who had medical issues requiring readmission (0.9%). There were no cases of dislocation or early loosening. Patients experienced significant improvements in their patient-reported outcome measures at both the 6-week mark and at the final postoperative follow-up visit (P < 0.0001).

CONCLUSIONS

The recently introduced femoral stem appears to be a safe and effective implant option in the short-term postoperative period, resulting in low complication rates and high levels of patient satisfaction. Future longer-term follow-up studies are necessary to fully characterize its risk profile and effectiveness.

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.

Do all anatomic stems perform equally at long-term survival? A regional registry-based study on 12,010 total hip arthroplasty implants according to stem length and neck modularity

BACKGROUND

Anatomic stems for total hip arthroplasty (THA) have been developed to achieve a precise geometric fit between the implant and the surrounding femoral bone, aiming at the improvement of primary stability of cementless implants until osteointegration occurs. The aim of the current study is to go over the regional Registry of Orthopaedic Prosthetic Implants (RIPO) to analyze survivorship of THA implants when anatomic stems are used; moreover, separate analysis for modular and nonmodular stems, and in standard and short implants, is presented.

MATERIALS AND METHODS

This retrospective registry study involved the analysis of data collected by the RIPO registry between 2000 and 2019. The study focused on THAs performed for primary hip osteoarthritis (OA) between 2000 and 2019. All patients treated by THA within this time frame and officially registered in the RIPO registry were included in the study. Exclusion criteria were: revision THAs, cemented implants, hemiarthroplasties, resurfacing procedures, megaprostheses for neoplastic and non-neoplastic conditions, and THAs performed on patients residing outside the region.

RESULTS

A total of 12,010 cementless primary THAs using curved anatomic stems were performed in Emilia-Romagna between 2000 and 2019 and formally registered in the RIPO registry. The overall survival rate for anatomic standard stems was 96.7% at 10 years (96.1-97.3%); at 15 from the surgery, the survival rate dropped to 95.1% (93.9-96.1%). A total of 473 out of 12,010 recorded THA with anatomic stems (3.93%) experienced failure requiring revision surgery. The fixed standard stem showed the lowest failure rate (0.6%), while modular short stems had the highest (7.4%) at long-term follow-up. The most common stem-related complication was periprosthetic fracture (PF) in short stems (2.0% of cases) while in standard stems it was implant breakage (0.9% of cases); PFs were significantly more frequent in female patients (p = 0.0082), with a relative risk (RR) of 1.59 compared with male patients. Implant breakage demonstrated the highest rate of incidence among standard-modular stems (1.1% of cases).

CONCLUSIONS

This registry-based study highlights that stem length and modularity significantly affect the long-term survival of anatomic femoral stems in THA. Fixed standard stems had the lowest failure rates, while modular short stems showed the highest failure rates and complications.

LEVEL OF EVIDENCE: 3

Performance of Cementless Hip Arthroplasty Stem Types Based on Consolidated Large Registry Data

Background

Improvements in cementless total hip arthroplasty have been directed at optimizing osseointegration of the femoral implant to reduce aseptic loosening rates. Stem design plays a critical role in the performance of these implants. Given the increase in new stem designs and the creation of an updated classification system, improved understanding of the outcomes of each stem type is warranted. The purpose of this study was to determine overall revision rates based on stem design and proprietary model.

Methods

Joint registry data on the reported overall cases and revisions for each cementless stem brand were collected from the annual reports of the American Joint Replacement Registry (2021), United Kingdom National Joint Registry (2021), New Zealand Joint Registry (2020), and Australian Orthopaedic Association National Joint Replacement Registry (2021). Each individual stem brand was classified into a stem type derived from the classification system described by Radaelli et al.

Results

The most utilized stem types were (1) type B2 stems, (2) type A stems, and (3) type C1 stems. The most utilized stem models were the (1) Corail stem (B2), (2) Accolade II (type A), and (3) Taperloc 133 (type A). The highest and lowest overall revision rates observed were in the type B1 stems (8.09%) and type C3 stems (1.12%), respectively. The 3 stem models with the highest overall revision rates were the Synergy HA stem (9.04%), CBC stem (8.59%), and CLS stem (7.96%). The 3 stems with the lowest respective overall revision rates were the C2 stem (0.00%, 0 of 933 cases), Actis Duofix (0.59%), and VerSys stem (0.89%).

Conclusions

Based on consolidated large registry data, some cementless femoral stem types and models appear to perform better than others when compared on the basis of stem design.

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.

Influence of Femoral Stem Geometry on Total Hip Replacement: A Comparison of Clinical Outcomes of a Straight and an Anatomical Uncemented Stem

Background/Objectives: There are many aspects that may influence clinical outcomes in a total hip arthroplasty (THA). The influence of femoral stem on the clinical outcome of THA is probably underestimated in the literature. Our work aims to analyze how uncemented stem geometry (straight or anatomical) in THA might affect outcomes in clinical and radiographic terms. Methods: Over a period of 36 months, in a prospective-observational manner, we collected the results of THA secondary to osteoarthritis (OA) that met the inclusion criteria with the only variable being the straight or anatomical stem design in a single manufacturer. A total of 84 patients were selected and divided into two groups: group A, treated with straight stem (44 patients), and group B, treated with anatomical stem (40 patients). The assessment clinical tools were Harris Hip Score (HHS), Visual Analogue Scale (VAS), and Short Form Health Survey-36 (SF-36). Follow-up controls were at 6 months (T0), 12 months (T1), 24 months (T2), and 36 months (T3). Results: No statistically significant differences emerged between the two groups under analysis with VAS, SF-36, and HHS. At follow-up controls, eight patients (group A) and four patients (group B) showed anterior thigh pain. At T1, there were radiographic signs of aseptic loosening in two cases (group A) and one case (group B). In group A there were two cases of iatrogenic fracture, two cases of dislocation, one case of infection, and two cases of heterotopic ossification. Conclusions: The anatomical stem compared to the straight stem showed lower complication rates outcomes; the anatomical uncemented stem could be considered as a preferred first choice in THA compared to the straight stem.

Impact of fixation method on femoral bone loss: a retrospective evaluation of stem loosening in first-time revision total hip arthroplasty among two hundred and fifty five patients

PURPOSE

Implant loosening represent the most common indication for stem revision in hip revision arthroplasty. This study compares femoral bone loss and the risk of initial revisions between cemented and uncemented loosened primary stems, investigating the impact of fixation method at primary implantation on femoral bone defects.

METHODS

This retrospective study reviewed 255 patients who underwent their first revision for stem loosening from 2010 to 2022, receiving either cemented or uncemented stem implants. Femoral bone loss was preoperatively measured using the Paprosky classification through radiographic evaluations. Kaplan-Meier analysis estimated the survival probability of the original stem, and the hazard ratio assessed the relative risk of revision for uncemented versus cemented stems in the first postoperative year and the following two to ten years.

RESULTS

Cemented stems showed a higher prevalence of significant bone loss (type 3b and 4 defects: 32.39% vs. 2.72%, p < .001) compared to uncemented stems, which more commonly had type 1 and 2 defects (82.07% vs. 47.89%, p < .001). In our analysis of revision cases, primary uncemented stems demonstrated a 20% lower incidence of stem loosening in the first year post-implantation compared to cemented stems (HR 0.8; 95%-CI 0.3-2.0). However, the incidence in uncemented stems increased by 20% during the subsequent years two to ten (HR 1.2; 95%-CI 0.7-1.8). Septic loosening was more common in cemented stems (28.17% vs. 10.87% in uncemented stems, p = .001). Kaplan-Meier analysis indicated a modestly longer revision-free period for cemented stems within the first ten years post-implantation (p < .022).

CONCLUSION

During first-time revision, cemented stems show significantly larger femoral bone defects than uncemented stems. Septic stem loosening occurred 17.30% more in cemented stems.

Femoral Component Design Is Associated With the Risk of Periprosthetic Femur Fracture After Cementless THA in Patients 65 Years or Older

BACKGROUND

Periprosthetic femur fracture is a known complication after THA. The associated risk of cementless femoral component design for periprosthetic femur fracture in a registry population of patients older than 65 years has yet to be clearly identified.

QUESTIONS/PURPOSES

(1) Is femoral stem geometry associated with the risk of periprosthetic femur fracture after cementless THA? (2) Is the presence or absence of a collar on cementless femoral implant designs associated with the risk of periprosthetic femur fracture after THA?

METHODS

We analyzed American Joint Replacement Registry data from 2012 to March 2020. Unique to this registry is the high use of cementless femoral stems in patients 65 years and older. We identified 266,040 primary cementless THAs during the study period in patients with a diagnosis of osteoarthritis and surgeries linked to supplemental Centers for Medicare and Medicaid data where available. Patient demographics, procedure dates, and reoperation for periprosthetic femur fracture with revision or open reduction and internal fixation were recorded. The main analysis was performed comparing the Kheir and Chen classification: 42% (112,231 of 266,040) were single-wedge, 22% (57,758 of 266,040) were double-wedge, and 24% (62,983 of 266,040) were gradual taper/metadiaphyseal-filling cementless femoral components, which yielded a total of 232,972 primary cementless THAs. An additional analysis compared cementless stems with collars (20% [47,376 of 232,972]) with those with collarless designs (80% [185,596 of 232,972]). A Cox proportional hazard regression analysis with the competing risk of death was used to evaluate the association of design and fracture risk while adjusting for potential confounders.

RESULTS

After controlling for the potentially confounding variables of age, sex, geographic region, osteoporosis or osteopenia diagnosis, hospital volume, and the competing risk of death, we found that compared with gradual taper/metadiaphyseal-filling stems, single-wedge designs were associated with a greater risk of periprosthetic femur fracture (HR 2.9 [95% confidence interval (CI) 2.2 to 3.9]; p < 0. 001). Compared with gradual taper/metadiaphyseal-filling stems, double-wedge designs showed an increased risk of periprosthetic femur fracture (HR 3.0 [95% CI 2.2 to 4.0]; p < 0. 001). Collarless stems showed an increased risk of periprosthetic fracture compared with collared stems (HR 7.8 [95% CI 4.1 to 15]; p < 0. 001).

CONCLUSION

If cementless femoral fixation is used for THA in patients 65 years or older, surgeons should consider using gradual taper/metadiaphyseal-filling and collared stem designs because they are associated with a lower risk of periprosthetic femur fracture. Future investigations should compare gradual taper/metadiaphyseal-filling and collared cementless designs with cemented fixation in this population.

LEVEL OF EVIDENCE

Level III, therapeutic study.

Analysis of Postoperative Complication and Revision Rates and Mid- to Long-Term Implant Survival in Primary Short-Stem Total Hip Arthroplasty

Background/Objectives: Short-stem prostheses were introduced as an alternative to conventional straight-stem prostheses. Despite their benefits, including minimally invasive approaches, soft-tissue- and bone-sparing implantation, and physiological load transfer to the metaphysis, data on postoperative complication and revision rates as well as on implant survival are scarce. Methods: A retrospective analysis of 1327 patients who underwent primary total hip arthroplasty (THA) using the Metha® short stem between 2006 and 2023 was conducted. Complication and revision rates were analysed for the intraoperative, direct postoperative, and follow-up episodes. Implant survival was analysed with the endpoint of all-cause stem revision. Results: Intraoperative complications were observed in 3.77% of the cases and included 44 hairline cracks and 6 fractures. In 15 cases (30.0%), conversion to a straight-stem or revision implant was necessary. The direct postoperative complication rate was 2.44%, and 11 revision procedures were performed during inpatient stay (0.84%). Mean follow-up was 7 years (range 1-17). During follow-up, femoral component revision was performed in 60 cases. Aseptic loosening and stem subsidence accounted for a combined percentage of 80% of all indications. Implant survival rate was 95.66% after 5 years, 95.58% after 10 years, and 95.50% after 15 years. Conclusions: Our study provides a comprehensive analysis of postoperative complication and revision rates in a large sample undergoing primary short-stem THA. Postoperative complication rates were favourable, and the long-term implant survival rates were comparable to conventional straight-stem prostheses. Therefore, short-stem THA may be considered an alternative for younger patients.

Vibratory insertion of press-fit acetabular components requires less force than a single blow technique

Aims

Periprosthetic fracture and implant loosening are two of the major reasons for revision surgery of cementless implants. Optimal implant fixation with minimal bone damage is challenging in this procedure. This pilot study investigates whether vibratory implant insertion is gentler compared to consecutive single blows for acetabular component implantation in a surrogate polyurethane (PU) model.

Methods

Acetabular components (cups) were implanted into 1 mm nominal under-sized cavities in PU foams (15 and 30 per cubic foot (PCF)) using a vibratory implant insertion device and an automated impaction device for single blows. The impaction force, remaining polar gap, and lever-out moment were measured and compared between the impaction methods.

Results

Impaction force was reduced by 89% and 53% for vibratory insertion in 15 and 30 PCF foams, respectively. Both methods positioned the component with polar gaps under 2 mm in 15 PCF foam. However, in 30 PCF foam, the vibratory insertion resulted in a clinically undesirable polar gap of over 2 mm. A higher lever-out moment was achieved with the consecutive single blow insertion by 42% in 15 PCF and 2.7 times higher in 30 PCF foam.

Conclusion

Vibratory implant insertion may lower periprosthetic fracture risk by reducing impaction forces, particularly in low-quality bone. Achieving implant seating using vibratory insertion requires adjustment of the nominal press-fit, especially in denser bone. Further preclinical testing on real bone tissue is necessary to assess whether its viscoelasticity in combination with an adjusted press-fit can compensate for the reduced primary stability after vibratory insertion observed in this study.

Strikingly High Rates of Periprosthetic Joint Infection Following Revision Surgery for Periprosthetic Fractures Regardless of Surgery Timing

BACKGROUND

Periprosthetic fractures following total hip arthroplasty (THA) often occur in the early postoperative period. Recent data has indicated that early revisions are associated with higher complication rates, particularly periprosthetic joint infection (PJI). The purpose of this study was to assess the effect of timing of periprosthetic fracture surgery on complication rates. We hypothesized that complication rates would be significantly higher in revision surgeries performed within 3 months of the index THA.

METHODS

The Medicare Part A claims database was queried from 2010 to 2017 to identify patients who underwent surgery for a periprosthetic fracture following primary THA. Patients were divided based on time between index and revision surgeries: <1, 1 to 2, 2 to 3, 3 to 6, 6 to 9, 9 to 12, and >12 months. Complication rates were compared between groups using multivariate analyses to adjust for demographics, comorbidities, and types of revision surgery.

RESULTS

Of 492,340 THAs identified, 4,368 (0.9%) had a subsequent periprosthetic fracture requiring surgery: 1,725 (39.4%) at <1 month, 693 (15.9%) at 1 to 2 months, 202 (4.6%) at 2 to 3 months, 250 (5.7%) at 3 to 6 months, 134 (3.1%) at 6 to 9 months, 85 (19.4%) at 9 to12 months, and 1,279 (29.3%) at >12 months. The risk of PJI was 11.0% in the <1 month group, 11.1% at 1 to 2 months, 7.9% at 2 to 3 months, 6.8% at 3 to 6 months, 8.2% at 6 to 9 months, 9.4% at 9 to 12 months, and 8.5% at >12 months (P = .12). Adjusting for confounding factors, risk of PJI following periprosthetic fracture surgery was similar regardless of timing (P > .05). Rates of subsequent dislocation and aseptic loosening were also similar regardless of timing.

CONCLUSIONS

The risk of PJI following repeat surgery for a periprosthetic fracture was strikingly high regardless of timing (6.8 to 11.1%), underscoring the high-risk of complications.

Hydroxyapatite-Coated Femoral Stems in Primary Total Hip Arthroplasty: An Updated Meta-Analysis

BACKGROUND

Most primary total hip arthroplasties (THAs) performed in the United States utilize cementless fixation with porous or hydroxyapatite (HA) coating. A previous meta-analysis comparing HA-coated versus non-HA-coated stems in primary THA published in 2013 found no significant difference between the 2. However, an updated analysis of the current literature is needed to assess the potential benefit of HA-coated stems in primary THA.

METHODS

Various libraries were searched through May 2022 according to Preferred Reporting Items for Systematic Reviews and Meta-analysis (PRISMA) guidelines. Studies included were randomized controlled trials comparing HA-coated femoral stems to non-HA-coated stems in primary THA. Outcomes included Harris Hip Score (HHS), endosteal bone formation, radiolucent lines, linear wear rate, revision for aseptic loosening, thigh pain, and heterotopic ossification.

RESULTS

There were significantly fewer revisions for aseptic loosening (P = .004) and decreased postoperative thigh pain (P = .03) for patients who have with HA-coated stems. There was no significant difference in HHS (P = .20), endosteal bone formation (P = .96), radiolucent lines (P = .75), linear wear rate (P = .41), or heterotopic ossification (P = .71) between HA-coated and non-HA-coated stems.

CONCLUSION

We found that HA-coated femoral stems in primary THA led to significantly fewer stem revisions for aseptic loosening and less postoperative thigh pain compared to non-HA-coated stems. These findings suggest HA-coated femoral stems should be preferred over non-HA-coated femoral stems in primary THA.

United States Experience With a Femoral Neck Retaining Total Hip Arthroplasty Stem: A Retrospective Study With Control Comparison From the Literature

BACKGROUND

Femoral neck retaining prostheses have gained popularity in Europe, but the United States has not seen the same trends occurring. Previous reports demonstrate high survivorship for these implants, but to our knowledge, there are no reports examining US data.

METHODS

After institutional review board approval, 824 primary total hip arthroplasties utilizing a femoral neck-retaining prosthesis were examined for femoral component survivorship rates. European studies were systematically reviewed to determine survivorship rates. The data were used to formulate a Kaplan-Meier survivorship curve and compare US data to that of the European studies.

RESULTS

European studies demonstrated survivorship rates for all causes of 97.7 and 99.0% for aseptic loosening at an average of 6 years (range, 4.5 to 10). The current study demonstrated an all-cause 94% Kaplan-Meier survivorship estimate at 5 years and when aseptic loosening only was considered, survivorship increased to 99.4% at 5 years and 98.4% at 11 years.

CONCLUSION

This femoral neck-retaining prosthesis demonstrated excellent survivorship that is comparable to the rates seen in European studies as well as the rates of standard and mid-stem prostheses in the United States.

Long-term survival and complication rate of cementless prosthetic stems in primary total hip arthroplasty categorized by types according to Mont classification: a regional registry-based study on 53,626 implants

INTRODUCTION

The purpose of this retrospective registry-based study is to assess survival and causes of failure of cementless stem implants used in total hip arthroplasty (THAs), to ascertain if there are differences when these are categorized according to the six types described by Mont.

METHODS

Data collected from the regional registry regarding all primary THAs performed from 2000 to 2019 were analyzed. Femoral prosthetic stems were divided into the six types of Mont classification. For each stem type, number of implants, survival and causes of failure were evaluated and compared.

RESULTS

The most frequently implanted stem type was the 3c type (53.4%). Type 1 had the lowest stem failure rate (1.6%), and type 6 showed the highest (3.9%). Periprosthetic fracture was the most frequent complication in type 6, accounting for 34.5% of failures. Aseptic loosening was the main complication in type 2 stems, accounting for 36.4% of failures. Pairwise comparisons showed significant higher survival of type 1 compared to type 3c (p = 0.000026) and type 6 (p = 0.000076), and between type 3a compared to type 3c (p = 0.03) and type 6 (p = 0.026).

CONCLUSION

Significant variations in implant survival rates were found among the six Mont-types of cementless stems. These findings emphasize the paramount importance of stem design and fixation area in determining long-term survival, providing a guidance for orthopedic surgeons in the selection of the most appropriate stem for primary THA, contributing to our understanding of cementless stem performance, presenting invaluable insights to further improve patient outcomes in THA surgery.

Novel radiologic indices for stem type decision in total hip arthroplasty in patients with metaphyseo-diaphyseal mismatched Dorr A proximal femur

BACKGROUND

In metaphyseo-diaphyseal (M-D) mismatched Dorr A femurs, it is difficult to achieve proper fixation with a type 1 stem. Proper interpretation of the geometry of the femur is integral at the preoperative stage in an M-D mismatched femur, but there has been a scarcity of studies on the radiologic indices. Therefore, we analyze the previous radiologic indices and suggest the novel ones for M-D mismatched femurs.

METHODS

Our study was a retrospective review of preoperative radiographs of patients who underwent total hip arthroplasty with the smallest type 1 stem or with type 3 C stem at a single institution from July 2014 to March 2022. A Type 3 C stem was used when the smallest type 1 stem failed to achieve metaphyseal fixation. One hundred twenty-six patients were categorized into two main groups. Canal-flare index, canal-calcar ratio, modified morphological cortical index, and two novel indices (lesser trochanter-to-distal ratio-α and -β [LDR-α and -β]) were assessed on preoperative pelvic radiographs.

RESULTS

Multivariate and ROC analysis demonstrated that high LDR-β (Exp[B]: 485.51, CI: 36.67-6427.97, p < 0.001) was associated with a more mismatched tendency group and had clinically acceptable discriminatory power (AUC: 0.765, CI: 0.675-0.855, p < 0.001) between the two cohorts.

CONCLUSION

Correct assessment of preoperative femoral morphology would be fundamental in the selection of a suitable stem. The ratio based on 3 cm below the lesser trochanter of the femur seemed crucial. We recommend evaluating the newly described radiological index preoperatively in M-D mismatched Dorr A femur for planning precisely and selecting a proper stem.

Design and Verification of a Metaphyseal Filling Stem for Total Hip Arthroplasty Based on Novel Measurements of Proximal Femoral Anatomy

Background

Cementless metaphyseal filling stems rely on fixation in the medial-to-lateral and anterior-to-posterior (AP) planes. The purpose of this preclinical study was to develop Insignia, a new metaphyseal filling system to match the anatomy of the proximal femur, and then compare it to clinically successful stems in multiple simulations.

Methods

In this preclinical study, the geometry of the proximal femur in the AP plane among 1321 healthy subjects was evaluated using computed tomography. This data was then used to design insignia. Preclinical studies were performed to compare the broaching effort required to prepare a canal using this system, assess the reliability of seating heights for the stem, and compare in vitro micromotion testing of the stem under simulated stair climb activity.

Results

The proximal femur decreased approximately 50% in the AP plane spanning 20 mm above the lesser trochanter to 30 mm below the lesser trochanter. Additional bench top testing was performed, and the new stem system was found to demonstrate significantly reduced broaching effort (average 6 vs 29 hits, P-value = .000), reliable seating heights on stem placement, and 70% less proximal micromotion on 10,000-cyclic testing (P < .05) compared to another clinically successful metaphyseal filling stem.

Conclusions

The AP dimension of the proximal femur decreases nearly 50% throughout its length. Metaphyseal filling stems that match the AP anatomy of the proximal femur may require fewer hits during broaching, yield reproducible seating heights, and reduce micromotion on cyclic testing.

No significant differences in 60-day postoperative complication rates between conventional and shortened stems

PURPOSE

To compare 60-day complication rates, radiographic outcomes, and clinical outcomes following primary THA with conventional versus shortened stems, in a large cohort study.

METHODS

The authors reviewed a consecutive series of 800 primary THAs, of which 781 met the inclusion/exclusion criteria: 395 received a conventional stem and 386 received a shortened stem. Intraoperative and postoperative complications were noted. Radiographic and clinical assessments were performed preoperatively and 60 days after surgery.

RESULTS

Compared to conventional stems, shortened stems had significantly less intraoperative complications (2.8% vs 0.3%, p = 0.006), but no significant differences in complications that did not require reoperation (1.0% vs 1.3%, p = 0.620), complications that required reoperation without stem revision (2.0% vs 1.0%, p = 0.384), and complications that required stem revision (0.5% vs 0.5%, p = 1.000). Four hips (two from each group) required stem revision and were thus excluded from 60-day assessment. There were no significant differences between groups in subsidence ≥ 3 mm (1.0% vs 0.5%, p = 0.686), alignment (90.3%vs 86.7%, p = 0.192), net change in offset (within 3 mm, 32.3% vs 30.5%, p = 0.097), and limb length discrepancy (3.0 ± 2.6 mm vs 2.9 ± 2.4 mm, p = 0.695). Compared to conventional stems, shortened stems had significantly better preoperative mHHS (56.5 ± 18.5 vs 64.5 ± 13.5, p < 0.001), and significantly lower net improvement in mHHS (29.9 ± 17.1 vs 24.4 ± 15.0, p < 0.001), but no significant differences in postoperative mHHS (87.3 ± 11.9 vs 89.4 ± 9.6, p = 0.109).

CONCLUSIONS

There were no significant differences between conventional and shortened stems in terms of postoperative complication rates, radiographic outcomes, and postoperative mHHS. However, patients implanted with shortened stems had less intraoperative complications, but lower net improvement in mHHS.

LEVEL OF EVIDENCE

Level IV, Retrospective comparative cohort study.

Rectangular Taper Stem Designs Are Associated With a Higher Risk for Periprosthstic Femoral Fractures After Cementless Total Hip Arthroplasty

BACKGROUND

Periprosthetic femoral fractures (PFFs) remain a major concern following cementless total hip arthroplasty (THA). This study aimed to evaluate the association between different types of cementless tapered stems and the risk of postoperative PFF.

METHODS

A retrospective review of primary THAs performed at a single center from January 2011 to December 2018 included 3,315 hips (2,326 patients). Cementless stems were classified according to their design. The incidence of PFF was compared between flat taper porous-coated stems (type A), rectangular taper grit-blasted stems (type B1), and quadrangular taper hydroxyapatite-coated stems (type B2). Multivariate regression analyses were performed to identify independent factors related to PFF. The mean follow-up duration was 61 months (range, 12 to 139). Overall, 45 (1.4%) postoperative PFFs occurred.

RESULTS

The incidence of PFF was significantly higher in type B1 stems than in type A and type B2 stems (1.8 versus 0.7 versus 0.7%; P = .022). Additionally, more surgical treatments (1.7 versus 0.5 versus 0.7%; P = .013) and femoral revisions (1.2 versus 0.2 versus 0%; P = .004) were required for PFF in type B1 stems. After controlling for confounding variables, older age, diagnosis of hip fracture, and use of type B1 stems were significant factors associated with PFF.

CONCLUSION

Type B1 rectangular taper stems were found to have higher risks for postoperative PFF and PFF requiring surgical management than type A and type B2 stems in THA. Femoral stem geometry should be considered when planning for cementless THA in elderly patients who have compromised bone quality.

Outcomes of direct anterior approach for uncemented total hip replacement in medial femoral neck fractures: a retrospective comparative study on the first 100 consecutive patients

BACKGROUND

With the aging of the population, the incidence of medial femoral neck fractures is likely to increase, and along them the need for total hip replacement. The present study aimed to analyze whether the use of the direct anterior hip approach, compared with posterolateral approach in medial proximal femur fracture patients, results in any advantage in terms of complications rate and functional recovery.

METHODS

A total of 162 patients were included in the study, and divided by approach: 100 performed with direct anterior approach (group A) and 62 with posterolateral approach (group B). The two populations were overlapping in age (75 vs 74 years; p = 0.13), sex (58F 42M vs 46F 16M; p = 0.12) and BMI (24 vs 24; p = 0.77).

RESULTS

Group A showed a higher ASA score compared to group B (3 vs 2; p = 0.04). Similar hospital stays (7 vs 7 days; p = 0.55) and complication rates (6% vs 8%; p = 0.61) were observed among groups, the most frequent being periprosthetic fractures, and need for allogeneic blood transfusion (20% vs 13%; p = 0.25). Patients in group A (96 vs 85 min; p = 0.10) showed a slightly, longer surgical time and a faster postoperative functional recovery witnessed by the ability to climb stairs at hospital discharge (37% vs 21%; p = 0.041).

CONCLUSION

The use of the direct anterior hip approach was effective in the management of frail patients with medial femoral neck fractures managed by total hip arthroplasty, allowing faster functional recovery in the elderly population.

Can Selected Use of Cemented and Uncemented Femoral Components in a Broad Population Produce Comparable Results Following Primary Total Hip Arthroplasty for Osteoarthritis?

BACKGROUND

Registry data have demonstrated lower rates of revision and periprosthetic fracture in select cohorts with cemented femoral fixation at primary total hip arthroplasty. Whether this is true of all component designs is not known. We hypothesized that selected use of ream-and-broach triple-tapered uncemented stem designs may provide comparable results to cemented stems.

METHODS

From 2000 to 2018, 5,809 primary total hip arthroplasties were performed with either a cemented (1,304) or ream-and-broach triple-tapered uncemented stem (4,505). Implant choice was at surgeon discretion. The cemented group was older, more often women, and had slightly lower body mass index. A subgroup analysis was performed on patients ≥75 years of age. Statistical weighting accounted for baseline cohort differences.

RESULTS

At 10 years, there was a trend toward higher all-cause revision (hazards ratio (HR) 1.6, P = .053) and higher all-cause reoperation (HR 1.6, P = .02) in the cemented fixation cohort. The cemented fixation group had fewer intraoperative periprosthetic fractures (HR 0.21, P < .001) but no difference in postoperative fractures (HR 0.99, P = .96). The same was true in patients ≥75 years. In the ≥75-years subgroup, there was no difference in revision or reoperation at 10 years.

CONCLUSION

Compared to cemented stems, the use of ream-and-broach triple-tapered uncemented stems in select patients, including those ≥75 years, was associated with more intraoperative fractures but no difference in 10-year implant survivorship. These findings are different than some registry data and suggest that specific uncemented components, implanted in selected patients by experienced surgeons, can perform as well as cemented implants in a broad patient population.

Digital Templating of THA Using PACS and an iPhone or iPad is as Accurate as Commercial Digital Templating Software

BACKGROUND

Digital templating is a standard preoperative planning method in THA. Unfortunately, many hospitals cannot afford the software or have accessibility barriers owing to a limited number of installed computer workstations. We created a templating method using a picture archiving and communication system and the Keynote program on a mobile phone. The method's accuracy and reliability have not been compared with those of commercial digital templating software.

QUESTIONS/PURPOSES

(1) How accurate is this novel method on iPhone and iPad mobile devices compared with a commercially available digital templating software program? (2) Is the method reproducible among users with different levels of experience? (3) Are the results similar for different types of femoral prostheses?

METHODS

Between January 2017 and May 2020, we treated 209 patients for hip disease or trauma with primary cementless THA. We considered patients with a normal contralateral hip as potentially eligible for this retrospective study. Thus, 91% (191 of 209 hips) were eligible; a further 13% (27 hips) were excluded because of postoperative leg length discrepancy > 5 mm, femoral offset discrepancy > 5 mm (9% [18 hips]), intraoperative periprosthetic fracture (4% [eight hips]), and proximal femoral deformity (0.5% [one hip]), leaving 78% (164 hips) for analysis here. Their preoperative radiographs were evaluated by three independent assessors, including one senior orthopaedic surgeon, one senior resident, and one junior resident, using three methods. The first was digital templating using OrthoView software, which is a commercially available digital templating software program used worldwide and known to possess high accuracy. The other two methods were technically similar to one another, with the only difference being the interface: iPhone versus iPad. In both of those approaches, using the picture archiving and communication system measurement tool, we drew a circle on an acetabular radiograph to depict the cup. We took a photograph of the computer display and imported the photograph into slides of the Keynote program, a presentation software application for Mac computers, on both devices. It was then underlaid on transparent digital templates of the femoral stem, which were scanned from plastic templates and positioned at the center of each slide. We scaled the image to the template by adjusting the image size until a 15-cm straight line on the hip photograph was equal to the 15-cm scale markers of the template. All templating results were compared with the actual implanted cementless THA components to assess accuracy. All assessors were blinded to the information about the actual implants, and they were not involved in performing the surgical procedures. The intrarater and interrater reliabilities were analyzed using intraclass correlation coefficients and kappa values. The accuracy for predicting stem size for each type of the four stem designs was compared among the three methods.

RESULTS

We were able to predict the acetabular cup size within one size in 92% of hips (151 of 164) using OrthoView and in 92% (150 of 164) using the novel method (p > 0.99). The accuracies of the three methods were comparable for predicting a femoral stem size within one size (OrthoView: 90% [148 hips], iPhone: 93% [152 hips], and iPad: 91% [149 hips]; p = 0.78), and neck length (OrthoView: 96% [157 hips], iPhone: 96% [158 hips], and iPad: 97% [159 hips]; p = 0.95). Using OrthoView, the neck offset was correctly predicted in 80% (132 hips), compared to 85% (139 hips) when using the iPhone and 82% (134 hips) when using the iPad (p = 0.57). All methods showed substantial or excellent agreement regarding intrarater and interrater reliability. There was no difference in accuracy regarding any of the four femoral stem designs we evaluated (Avenir, Excia, ML taper, and Metha).

CONCLUSION

The digital templating technique for THA using an iPhone or iPad combined with a picture archiving and communication system demonstrated high accuracy, comparable to that of commercial digital templating software. This technique is reliable and reproducible for predicting a cementless prosthesis size, neck length, and offset in different types of femoral stems. It may be useful as an alternative in resource-constrained centers where commercial software programs are too expensive to be used in practice.

LEVEL OF EVIDENCE

Level IV, diagnostic study.

Outcomes of Nonoperatively Treated Vancouver B1 Fractures: Is Failure Common?

BACKGROUND

Periprosthetic fractures (PPFx) are a severe complication of total hip and hemiarthroplasty. Surgical treatment is typically performed but can result in major morbidity. Nonoperative PPFx management may provide a successful treatment alternative in select patients.

METHODS

Vancouver B1 PPFx patients treated over a 10-year period were identified. Patient demographic data were retrospectively recorded. Injury and postoperative radiographs were reviewed. There were 48 patients who met the study criteria. Patients were divided into operative and nonoperative comparative cohorts. Outcome comparisons between the 2 cohorts included 1-year mortality, unplanned surgery within 24 months of injury, fracture union rate, and return to preinjury ambulation status.

RESULTS

There was no difference in 1-year mortality between the nonoperative and operative cohorts (17 versus 8%; P = .32). We found no significant difference in unplanned surgery between the nonoperative and operative groups (8.7 versus 12%; P = .71), fracture union (100 versus 96%, P = .34), or return to ambulation status (86 versus 91%; P = .86). Nonoperative fractures were minimally displaced and within the metaphyseal region of the proximal femur without stem subsidence. Nonoperative fractures with subsequent treatment failure had initial fracture extension closer to the tip of the stem compared to successfully treated nonoperative fractures (5.5 versus 10.2 centimeters; P = .02).

CONCLUSION

Select nonoperatively treated patients had infrequent need for unplanned surgery, high union rate, and return to their preinjury ambulation status. Nonoperative management is not appropriate for all Vancouver B1 PPFx, but those patients who have minimally displaced meta-diaphyseal fractures and partial remaining distal fixation can be successfully treated.

A New Classification System for Cementless Femoral Stems in Total Hip Arthroplasty

BACKGROUND

The growing variety of total hip arthroplasty implants necessitates a standardized, simple, and brand-neutral language to precisely classify femoral components. Although previous classifications have been useful, they need updating to include stems that have current surface treatment technologies, modularity, collar features, and other geometric characteristics.

METHODS

To accomplish this, we propose a new classification system for stems based on 3 distinguishing stem features: (1) geometry, (2) location of modularity, and (3) length.

RESULTS

Our system allows for the easy classification of all currently used stem types.

CONCLUSIONS

One goal of this endeavor is to improve clinical record keeping to facilitate study comparisons as well as literature reviews.

Bionic reconstruction of tension trabeculae in short-stem hip arthroplasty: a finite element analysis

BACKGROUND

Short-stem hip arthroplasty (SHA) is characterized by metaphyseal load transfer that effectively preserves the bone stock, but still suffers from stress shielding in the proximal femur. We designed a tension screw to mimic tension trabeculae in the new bionic collum femoris preserving (BCFP) short stem for bionic reconstruction, aiming to restore the biomechanics of hip joint.

METHODS

Native femur finite element model was constructed to investigate the biomechanics of hip joint based on computed tomography (CT) data. The maximum absolute principal stress/strain cloud chart allowed the direction of stress/strain to be assessed. Six BCFP models with different screw angles (5°, 10°, 15°, 20°, 25°, and 30°) and the Corail model were created. The stress/strain distribution and overall stiffness were compared between each of the BCFP and Corail implanted models.

RESULTS

The native model visualized the transfer pathways of tensile and compressive stress. The BCFP stems showed significantly higher stress and strain distribution in the greater trochanteric region compared to conventional total hip arthroplasty (THA). In particular, the BCFP-5° stem demonstrated the highest average strain in both medial and lateral regions and the overall stiffness was closest to the intact femur.

CONCLUSIONS

Stress transfer pathways of trabecular architecture provide biomechanical insight that serves as the basis for bionic reconstruction. The tension screw improves load transfer pattern in the proximal femur and prevents stress reduction in the greater trochanteric region. The BCFP-5° stem minimizes the stress shielding effect and presents a more bionic mechanical performance.

The Knee-Fix study: study protocol for a randomised controlled trial evaluating cemented and cementless components in total knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is an effective procedure for patients with a variety of knee conditions. The main cause of aseptic TKA failure is implant loosening, which has been linked to poor cement mantle quality. Cementless components were introduced to offer better longer-term biological fixation through osseointegration; however, early designs led to increased rate of revision due to a lack of initial press-fit and bony ingrowth. Newer highly porous metal designs may alleviate this issue but randomised data of fully uncemented TKA (tibial, femoral, patella) is lacking. The aim of the Knee-Fix study is to investigate the long-term implant survival and patient outcomes of fully uncemented compared with cemented fixation in TKA. Our study hypothesis was that uncemented TKA would be as clinically reliable and durable as the gold-standard cemented TKA.

METHODS

The Knee-Fix study is a two-arm, single-blinded, non-inferiority randomised controlled trial with 160 patients in each arm and follow-up at 6 weeks, 6 months, 12 months, 24 months, 5 years and 10 years. The primary outcome of interest is implant fixation, which will be measured by assessment of postoperative progressive radiolucencies with the Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. Secondary outcome measures are patient-reported outcomes, measured using Oxford Knee Score (OKS), International Knee Society System (IKSS), Forgotten Joint Score-12 (FJS-12), EuroQol (EQ-5D-5L), VAS Pain, Patient Satisfaction Score and Net Promoter Score.

DISCUSSION

While cemented fixation remains the gold standard, a growing proportion of TKA are now implanted cementless. Highly porous metal cementless components for TKA can offer several benefits including potentially improved biological fixation; however, long-term outcomes need further investigation. This prospective study will help discern long-term differences between the two techniques.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12616001624471 . Registered trial name: Knee-Fix study (Cemented vs Uncemented Total Knee Replacement). Registered on 24 November 2016.

Single Wedge Femoral Stem Designs are Associated With a Higher Risk for Revision After Cementless Primary Total Hip Arthroplasty

BACKGROUND

Cementless total hip arthroplasty (THA) femoral stems are the most commonly selected prostheses in the United States. Optimal stem geometry remains controversial with excellent survivorship reported for many designs. We compared cause-specific stem revision of single-wedge versus double-wedge designs from a multicenter US cohort.

METHODS

Data from an integrated healthcare network's total joint replacement registry were used to conduct a cohort study. Primary elective cementless THAs were identified (2001 to 2018). Implant exposure groups were classified by design geometry using the system proposed by Khanuja et al. Type 1 single-wedge (n = 11,082) and type 2 double-wedge (n = 32,380) designs were compared, and other design types were excluded; the final study cohort comprised 43,462 THAs. Cause-specific multivariable Cox regressions were used to evaluate risk for revision due to infection or aseptic reasons, including loosening, instability, periprosthetic fracture, or other reasons.

RESULTS

After adjustment for covariates, a higher aseptic revision risk was observed for type 1 when compared to type 2 designs (hazard ratio = 1.91, 95% confidence interval = 1.33-2.75). When looking at specific revision reasons, revision for aseptic loosening (hazard ratio = 3.46, 95% confidence interval = 2.24-5.34) was higher for type 1 versus type 2 designs. No differences were found for septic revision, instability, periprosthetic fracture, or revisions for other reasons.

CONCLUSIONS

Type 1 single-wedge designs were found to have a higher risk of revision due to aseptic loosening relative to type 2 double-wedge designs. Femoral stem geometry should be considered when selecting a cementless femoral implant.

LEVEL OF EVIDENCE

Level III.

Hip Arthroplasty Femoral Stem Designs and Their Association With Early Postoperative Periprosthetic Femoral Fractures

BACKGROUND

Periprosthetic femoral fractures (PFFs) in total hip arthroplasty (THA), especially those in contact with the diaphyseal stem, carry high morbidity. This study evaluated how stem design influences the risk of early Vancouver B PFF or other PFF requiring operative intervention after THA.

METHODS

A multicenter, retrospective study of 3,433 primary cementless THAs performed from 2014 to 2021 included 2,302 single-taper (micro M/L [n = 1,169]; M/L [n = 1,133]) and 1,131 double-taper (fit-and-fill [n = 420]; compaction-collared [n = 711]) stems. Mean follow-up was 2.2 years (range, 0.3 to 6.5 years). Primary outcomes were Vancouver B and surgically treated postoperative PFFs among differing femoral stems. Secondary outcomes included rates of intraoperative and postoperative Vancouver A and C PFFs.

RESULTS

Forty five postoperative PFFs (1.3%) occurred within 8.8 weeks (median), 25 of which were Vancouver B (0.7%) and 20 total PFFs that required operative intervention (0.6%). Compaction-collared stems had a decreased risk of Vancouver B (hazard ratio 0.18, 95% confidence interval: 0.03-0.97 P = .044) and any surgically treated PFF (hazard ratio 0.10, 95% confidence interval: 0.01-0.95; P = .037). Intraoperative PFFs were most common with fit-and-fill stems (3.6%, P < .001) and Vancouver A with compaction-collared stems (1.8%, P < .001). The cohort with PFF had a higher Charlson comorbidity index (P = .004), more women (P = .001), more Dorr A or C femora (P = .013), and more posterior or lateral surgical approaches compared to those without PFF (P ≤ .001).

CONCLUSION

After controlling for confounding variables, compaction-collared stems had a significantly lower risk of postoperative Vancouver B and PFF requiring operative treatment than single-taper and double-taper stems.

The short-term outcomes of cementless stem for hip arthroplasty in the elderly patients: comparison with patients < 65 years

OBJECTIVE

The use of cement or cementless femoral stem prosthesis for hip arthroplasty in elderly patients has been controversial. This study investigated the efficacy and safety of cementless femoral stem in elderly patients (age ≥ 65 years).

METHODS

The short-term efficacy of primary hip arthroplasty with cementless femoral stem in our hospital from January 2014 to June 2021 was retrospectively analyzed. Patients were divided into two groups according to age: young group (< 65 years) and the elder group (≥ 65 years). The evaluation index was the Harris Hip score (Harris), postoperative femoral stem prosthesis sinking distance and femoral plant-related complications (periprosthetic fracture, prosthesis loosening, infection, dislocation, etc.).

RESULTS

There were 72 cases of 86 hips in the young group and 83 cases of 92 hips in the elder group. The recovery trend of functional score in the elder group was similar to that in the young group, and the Harris score increased from (38.35 ± 18.21) before surgery to (86.91 ± 12.55) at last follow-up (p < 0.01). Compared with the two groups at the same time of 3 months, 6 months and 12 months after operation, the sinking distance of the elder group was significantly greater (P < 0.05). Even in the elder group, there was a significant difference in sinking distance between 6 and 3 months after surgery (2.44 ± 0.49 mm vs 2.10 ± 0.65 mm, P = 0.004). However, there was no significant difference between 12 and 6 months (2.53 ± 0.53 mm vs 2.44 ± 0.49 mm, P = 0.40). A total of 10 patients in the elder group and 6 patients in the young group had a complication event (P = 0.36).

CONCLUSIONS

Elderly patients with cementless femoral stems can achieve metal-bone integration slightly longer than young patients, but short-term clinical outcomes can be restored to a satisfactory level with adequate safety. However, the long-term efficacy still needs to be verified by multicenter, large sample size and prospective clinical follow-up results.

Selecting a Press-fit Stem for Total Hip Arthroplasty: The Rationale and Evolution of the Modern Femoral Prosthesis

Noncemented press-fit femoral stems predominate in total hip arthroplasty for all age groups with generally excellent long-term survivorship. The 2021 American Joint Replacement Registry reports that 96% of all elective primary total hip arthroplasties used noncemented femoral implant fixation. 1 Today, there are many styles of press-fit stems, each with supposed benefits, based on a range of design philosophies. Design aspects to consider when selecting a stem are numerous, including stem geometry, stem length, collared or collarless, material properties, and surface structure. Although most stem designs demonstrate excellent results, the differences in stem designs are intimately linked to additional factors such as ease of use/implantation, percentage of surface osseointegration, overall bone removal versus bone stock preservation, subsequent femoral stress shielding, and consideration of complexity of later revision. A surgeon with a broad understanding and appreciation of femoral stem designs should be prepared to select between the multitude of options to best serve individual patients.

Cemented Femoral Fixation in a High-Risk Cohort Diminishes Risk of Early Postoperative Periprosthetic Fracture

BACKGROUND

Early periprosthetic fractures (PPFx) following primary total hip arthroplasty (THA) create significant morbidity. Established risk factors for early PPFx include age, gender, body mass index, surgical approach, and implant fixation. We investigated the role of femoral fixation on early PPFx (<90 days postoperatively) in a high-risk cohort undergoing direct anterior approach (DAA) THA.

METHODS

The final cohort comprised 344 consecutive patients (390 hips) with risk factors for PPFx (age >68 years and body mass index <25 kg/m2) who underwent primary DAA THA between May 4, 2009 and December 31, 2019 and had 90-day follow-up. Noncemented fixation was used in 229-hips, while cemented fixation was used in 161 hips. The primary outcome was early PPFx. Fisher's exact test was used for categorical variables, while t-tests were used to compare continuous variables.

RESULTS

We observed 8 early PPFx (2.1%), all fractures occurring in the noncemented group. Baseline demographics were similar but not equal, with the cemented group being older (78.0 versus 76.3 years; P = .004) with a greater proportion of females (91.9% versus 69.4%; P < .001). The rate of early PPFx was significantly higher with noncemented fixation compared to cemented fixation (3.5% versus 0.0%; P = .023). A post hoc power analysis confirmed sufficient power (1-β = 0.81).

CONCLUSION

Although baseline risk factors for early PPFx are not easily modifiable, surgical factors can be modified. Cemented fixation has the potential to markedly reduce the risk of early PPFx in high-risk patients undergoing DAA THA.

Femoral Component Undersizing and Alignment are Risk Factors for Early Periprosthetic Femur Fracture

BACKGROUND

Known risk factors for early periprosthetic femur fracture (PFF) following total hip arthroplasty (THA) include poor bone quality and the use of cementless implants. The association between femoral component size and alignment and the risk of early PFF is not well described. We evaluated radiographic parameters of femoral component sizing and alignment as risk factors for early PFF.

METHODS

From 16,065 primary cementless THAs, we identified 66 cases (0.41%) of early PFFs (<90 days from index THA) at a single institution between 2016 and 2020. Sixty early PFFs were (1:2) matched to 120 controls based on the femoral component model, offset, surgical approach, age, body mass index (BMI), and gender. Radiographic assessment of preoperative bone morphology and postoperative femoral component orientation included stem alignment, metaphyseal fill, and implant congruence with medial cortical bone. A multivariable logistic regression was built to identify radiographic risk factors associated with early PFF.

RESULTS

Markers of preoperative bone quality including canal calcar ratio (P = .003), canal flare index (P < .001), anteroposterior canal bone ratio (CBR) (P < .001), and lateral CBR (P < .001) were statistically associated with PFF. Distance between the medial cortical bone and implant was greater in cases of PFF (2.5 mm vs 1.4 mm) (P < .001). A multivariate analysis demonstrated that a larger lateral metaphyseal CBR (Odds Ratio [OR] 5), valgus implant alignment (OR 5), and medial implant-bone incongruity (OR 2) increased the risk of early PFF.

CONCLUSION

A larger lateral metaphyseal CBR, valgus component alignment, and implant incongruity with medial cortical bone posed the greatest radiographic risk for early PFF following cementless THA.

Intermediate to Long-Term Outcomes and Causes of Aseptic Failure of an At-Risk Femoral Stem

BACKGROUND

The Accolade TMZF is a tapered-wedge cementless metaphyseal-coated femoral stem that was widely utilized from 2002 to 2012. In recent years, there have been reports of early catastrophic failure of this implant. The purposes of the present study were to establish the long-term survival of this stem and to analyze patients who underwent aseptic revision to understand the causes and risk factors for failure.

METHODS

We retrospectively reviewed the records of all patients who had undergone primary total hip arthroplasty with use of an Accolade TMZF stem at a high-volume arthroplasty center. The causes and timing of revision surgery were documented. Survivorship analysis was performed with use of Kaplan-Meier curves to determine the overall and aseptic survival rates at the time of the latest follow-up. Patient and implant factors commonly associated with aseptic failure were extracted, and a Cox proportional hazards model was used.

RESULTS

A consecutive series of 2,609 patients who had undergone unilateral primary total hip arthroplasty with use of an Accolade TMZF femoral stem were included. The mean time from the primary procedure was 11.3 years (range, 0 days to 19.4 years). The cumulative survival rate was 95.5% ± 0.1% at the time of the latest follow-up. One hundred and seven patients underwent revision surgery, with aseptic loosening of the femoral component being the most common cause of aseptic failure in this cohort (33 of 2,609; 1.3%). Smaller femoral size and larger femoral head offset were independent risk factors for aseptic failure.

CONCLUSIONS

To our knowledge, this is the largest series representing the longest follow-up of this tapered-wedge cementless femoral implant. Despite early concerns, the Accolade TMZF stem had excellent survivorship in this cohort. Trunnionosis as the cause for revision surgery was rare.

LEVEL OF EVIDENCE

Therapeutic Level IV. See Instructions for Authors for a complete description of levels of evidence.

Is there a role for cementless primary stem in hip arthroplasty for early or late fixation failures of intertrochanteric fractures?

Background

The choice of femur stems during the hip arthroplasty procedures for patients with treatment failure of intertrochanteric fractures (ITF) remains controversial. We aimed to compare the surgical complication and reoperation rates between cementless primary and revision stems in the early (≤3 months) and late (> 3 months) fixation failures of ITF.

Methods

This was a retrospective, cohort study conducted in a single, tertiary referral hospital of Taipei, Taiwan. We included hip arthroplasty procedures for failed ITF using cementless primary or revision stems. There were 40 and 35 patients who had early and late fixation failure of ITF, respectively. The patient demographics, time to fixation failure, surgical complications and medical complications were recorded for analysis.

Results

We included 75 patients that underwent hip arthroplasty procedure for failed ITF using cementless primary (n = 38) or revision (n = 37) stems. The mean age was 79.3 years and 56% of the patients were female. In the early fixation failure group, the complication rate was similar between the primary and revision stems (44% vs. 29%, p = 0.343). However, there was a trend toward a higher reoperation rate (31% vs. 8%, p = 0.061) of using the primary stem, compared with the revision stem. In the late fixation failure group, the rate of complication and reoperation was similar between the two stem types.

Conclusion

For early fixation failures of ITFs, we caution against the use of cementless primary stems due to a trend towards an increased risk of reoperations compared to the use of cementless revision stems. However, in late fixation failures of ITFs, there is a role for cementless primary stems.

Level of evidence

III, retrospective cohort study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12891-022-05223-x.

French Hip & Knee Society classification of short-stem hip prostheses: Inter- and intra-observer reproducibility

INTRODUCTION

In total hip replacement (THR), a short stem theoretically provides more physiological force transfer to the proximal femur, conserves bone stock and facilitates minimally invasive surgery. On the other hand, such implants involve a learning curve and incur risk of malpositioning or fracture and of secondary mobilization. There are several types of short stem, and classification is needed. Classifications exist, but are based more on implant length than on anchorage zone, and most have not been tested for reproducibility. The French Hip & Knee Society (SFHG) developed a short-stem classification based on anchorage zone inside the femur. The objectives of the present study were: (1) to present the classification, (2) to apply it to the short-stem models available in France and those widely used worldwide, and (3) to assess reproducibility.

HYPOTHESIS

The SFHG short-stem classification enables reproducible comparison.

MATERIAL AND METHOD

A short-stem classification according to anchorage zone was drawn up by an expert group. The stems and the classification were presented to 12 surgeons performing THR, who classified the stems according to the classification; a retest was performed 2 months later.

RESULTS

The classification is based on femoral stem anchorage site, in 5 types: type 1, cephalic; type 2, isolated cervical; type 3, Calcar femorale; type 4, metaphyseal; and type 5, conventional metaphyseal-diaphyseal, with shortened stems. Inter-observer reproducibility was 92.7% [95%CI: 91.7%-93.6%], with kappa 0.785 [95%CI: 0.755-0.814], and Lin test-rest concordance correlation coefficient 0.852 [95%CI: 0.836-0.869]. Intra-observer reproducibility was 94.0% [95%CI: 91.9%-96.1%], with kappa 0.820 [95%CI: 0.759-0.882], and Lin test-retest concordance correlation coefficient 0.820 [95%CI: 0.792-0.849].

DISCUSSION

This new classification enables femoral implants to be reproducibly compared according to anchorage zone.

LEVEL OF EVIDENCE

IV; retrospective study without control group.

Innovative Design Methodology for Patient-Specific Short Femoral Stems

The biomechanical performance of hip prostheses is often suboptimal, which leads to problems such as strain shielding, bone resorption and implant loosening, affecting the long-term viability of these implants for articular repair. Different studies have highlighted the interest of short stems for preserving bone stock and minimizing shielding, hence providing an alternative to conventional hip prostheses with long stems. Such short stems are especially valuable for younger patients, as they may require additional surgical interventions and replacements in the future, for which the preservation of bone stock is fundamental. Arguably, enhanced results may be achieved by combining the benefits of short stems with the possibilities of personalization, which are now empowered by a wise combination of medical images, computer-aided design and engineering resources and automated manufacturing tools. In this study, an innovative design methodology for custom-made short femoral stems is presented. The design process is enhanced through a novel app employing elliptical adjustment for the quasi-automated CAD modeling of personalized short femoral stems. The proposed methodology is validated by completely developing two personalized short femoral stems, which are evaluated by combining in silico studies (finite element method (FEM) simulations), for quantifying their biomechanical performance, and rapid prototyping, for evaluating implantability.

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.

Pneumatic femoral broaching decreases post-operative subsidence of a cementless taper-wedge stem

PURPOSE

Stem subsidence is a known cause of early failure in cementless total hip arthroplasty (THA). The aim of this study was to determine the usefulness of pneumatic femoral broaching in preventing post-operative subsidence of a proximally porous-coated, taper-wedge stem.

METHODS

We reviewed 169 cases of primary THA with a single taper-wedge stem. Eighty THAs performed using pneumatic broaching were compared with 89 THAs performed using manual broaching in terms of postoperative canal fill ratio (CFR) at three levels, stem subsidence at one year post-operation, and stem fixation at latest follow-up (median, 24 months).

RESULTS

The median CFRs were higher in the pneumatic group than in the manual group at all levels (p < 0.05). The median stem subsidence at one year after THA was lower in the pneumatic group than in the manual group (0.2 mm vs. 0.6 mm, p = 0.007). A multivariate analysis determined a decreased CFR at 60 mm below the lesser trochanter and the manual broaching as independent factors affecting post-operative stem subsidence. At the latest follow-up, all stems showed stable fixation by bone ingrowth in both groups.

CONCLUSION

Our results showed that the pneumatic broaching device was useful in maximizing the mediolateral canal filling and initial stability and minimizing the subsidence of taper-wedge stems.

Evaluation of the learning curve and initial outcomes with a short cervicometaphyseal fixation stem: A case series

INTRODUCTION

Total hip arthroplasty in young patients has evolved in recent decades, and the use of short stems in young adult patients has been gaining popularity. The restitution of the biomechanics of the hip is a primary requirement to determine the future success of total hip replacement, and even more so in young adults who present the particularity of having a high functional demand and a long life expectancy.

OBJECTIVE

The aim of this prospective study was to evaluate the learning curve and initial clinical-radiological outcomes of the Alteon Neck Preserving Stem™ (ANPS) (Exactech, Gainesville, FL, USA) with a minimum of 2 years follow up.

MATERIAL AND METHODS

We conducted a multicenter prospective study that analyzed 90 consecutive total hip replacements during 2014. We performed a clinical-radiological analysis measuring Harris Hip Score (HHS), subjective Rodes and Maudsley satisfaction evaluation, radiolucencies, components position, limb length discrepancy, heterotopic ossification, medical and surgical complications and learning curve.

RESULTS

During the first 30 cases, the intraoperative complication rate was 16%, while in the next 60 cases no intraoperative complications were reported. Thigh pain was reported in 3 cases (3.3%), being 2 moderates, and 1 severe. In 2 cases subsidences of 3 mm were detected in the first scheduled X-ray, both related to intraoperative fractures with no progression after 3 months. Mean HHS improved from 42.9 points (range 37-54 points) preoperatively to 93.2 on average (range, 87-96) at the end of the follow up (p < 0.01). Subjective evaluation was excellent in 75 (83.3%) cases and good in 15 patients (16.6%).

CONCLUSIONS

This short stem has good clinical radiological results in a short and medium term follow-up and in the hands of surgeons specializing in arthroplasty the learning curve is estimated to be less than 30 surgeries.

A Contemporary Classification System of Femoral Bone Loss in Revision Total Hip Arthroplasty

BACKGROUND

Current femoral bone loss classification systems in revision total hip arthroplasty were created at a time when the predominant reconstructive methods used cylindrical porous-coated cobalt-chrome stems. As these stems have largely been replaced by fluted-tapered titanium stems, the ability of these classification systems to help guide implant selection is limited. The purpose of this study was to describe a novel classification system based on contemporary reconstructive techniques.

METHODS

We reviewed the charts of all patients who underwent femoral component revision at our institution from 2007 through 2019. Preoperative images were reviewed, and FBL was rated according to the Paprosky classification and compared to ratings using our institution's NCS. Rates of reoperation at the time of most recent follow-up were determined and compared.

RESULTS

Four-hundred and forty-two femoral revisions in 330 patients with a mean follow-up duration of 2.7 years were identified. Femoral type according to Paprosky and NCS were Paprosky I (36, 8.1%), II (61, 13.8%), IIIA (180, 40.7%), IIIB (116, 26.2%), and IV (49 11.1%) and NCS 1 (35, 7.9%), 2 (364, 82.4%), 3 (8, 1.8%), 4 (27, 6.1%), and 5 (8, 1.8%). Of the 353 nonstaged rTHAs, there were 42 cases requiring unplanned reoperation (11.9%), including infection (18, 5.1%), instability (10, 2.8%), femoral loosening (5, 1.4%), and various other causes (9, 2.5%). The NCS was more predictive of reoperation than the Paprosky classification (Fisher's exact test, P = .008 vs P = ns, respectively).

CONCLUSION

We present a novel femoral classification system that can help guide contemporary implant selection.

Primary outcomes of a femoral neck-preserving stem: a multicentre clinical-radiological analysis at 5-year follow-up

PURPOSE

The aim of this prospective study was to evaluate the clinical-radiological outcomes of the Alteon Neck Preserving Stem (ANPS) (Exactech, Gainesville, FL, USA) implanted in four different centres by five senior hip surgeons with a minimum of 5 years of follow-up.

MATERIAL AND METHOD

We conducted a multicentre prospective study that analysed 155 consecutive total hip replacements during 2014. We performed clinical-radiological analysis measuring Harris Hip Score (HHS), subjective satisfaction evaluation, radiolucencies, position of components, limb length discrepancy, heterotopic ossification, medical and surgical complications and a survival analysis at 5 years follow-up.

RESULTS

Thigh pain was reported in 5 cases (3.2%), 2 of which reported mild pain, 2 moderate, and 1 severe. In 2 cases, subsidences of 3 mm were detected in the first scheduled X-ray, both related to intraoperative fractures with no progression after 3 months. The overall complication rate was 5.8% and 6 of the 9 complications were in the first 30 cases. Mean HHS improved from 42.9 points (range 37.2-55.7 points) preoperatively to 94.9 on average (range 87-98) at the end of the follow-up (p <0.01). Subjective evaluation was excellent in 130 (83.87%) cases and good in 25 patients (16.13%).

CONCLUSIONS

The clinical-radiographic results of ANPS THR are satisfactory. The mid-term results are promising. However, long-term follow-up studies are necessary to confirm the validity of the concept.