Press-fit vs threaded acetabulum components for total hip arthroplasty - A systematic review with metanalysis

Abstract

Background

Threaded acetabular components (TACs) have been shown to offer greater initial stability compared to press-fit acetabular components (PFACs). Despite these biomechanical advantages, the use of threaded cups remains. This study compares the outcomes of TACs to PFACs in total hip arthroplasty (THA), providing evidence-based data regarding their failure rates and radiological evaluation.

Methods

A meticulous research of PubMed and MEDLINE databases, following the PRISMA guidelines, was conducted, to identify all articles regarding the outcome of the use of TCAs compared to PFACs in THA. Subsequently, statistical analysis with metanalysis concerning: 1) the instances of revision due to aseptic loosening and 2) the radiological evaluations of TACs compared to PFACs and sensitivity analysis were performed.

Results

This metanalysis encompassed seven studies, enrolling 7878 cases of THA utilizing PFAC, and 6684 cases using TAC. The overall odds ratio (OR) for revision due to aseptic loosening in THA using PFAC compared to TAC was 3.10 (95 % CI 0.37–25.72). Additionally, when assessing radiolucency findings across the same categories, the pooled OR was 0.53 (95 % CI 0.26–1.08). An examination of studies with larger sample sizes revealed no statistically significant variance. After adjusting for age, no substantial difference was detected. However, upon gender adjustment, it was observed that females undergoing THA with PFAC had a 5-fold risk of revision (OR = 5.26, 95 % CI 0.25–111.91, p-value = 0.29) compared to females with TAC, although without reaching statistical significance. Moreover, females exhibited a slightly elevated risk for revision due to aseptic loosening post-PFAC THA compared to males [(OR = 5.26, 95 % CI 0.25–111.91) (OR = 2.51, 95 % CI 0.01–1051.68) respectively], and for radiolucency findings [(OR 0.74, 95 % CI 0.20–1.11) (OR 0.29, 95 % CI 0.03–3.36) respectively].

Conclusions

The PFACs remain the main option for total hip reconstruction, while TACs might be a viable alternative, especially in cases of osteoporosis.

1. Introduction

Total hip arthroplasty (THA) is one of the most cost-effective and consistently successful surgeries performed in orthopaedics and has been characterized as “the operation of the century”.¹ There have been steady advances in THA throughout the years. Improved understanding of cementing techniques, better acetabular and femoral component design, minimally invasive surgery (MIS) and refined implantation surgical techniques like computer-assisted navigation systems and robot-assisted surgery have led to significant improvements in implant survival and clinical outcomes.^{2, 3, 4, 5, 6}

Initially, in Charnley's low friction arthroplasty both the acetabular and the femoral components were fixed with cement, providing good results at that time.⁷ However, due to the high rates of aseptic loosening of the cemented acetabular sockets, related to so-called “cement disease”, and the poor results in young and active patients, new cementless acetabular cup implant designs and alternative solutions to bone fixation were developed.^7,8 Initial stability and fixation were achieved by press-fit of the cup component with or without additional attachment provided by pegs, screws or spikes or by threaded acetabulum prostheses.⁷

During the 1970s the initial cementless designs had smooth surface. These were the so-called “1st generation” cups, referring to both press-fit acetabular cups (PFACs) and threaded acetabular cups (TACs).^{7, 8, 9, 10} The 1st generation components exhibited high failure rates due to aseptic loosening and the absence of biological integration. The 2nd and 3rd generation components consisted of a metallic shell coated with porous or hydroxyapatite (HA) and exhibited good long-term results.^{7, 8, 9} Several elements influence the initial stability of acetabular cups before bone integration occurs. These factors include the shape of the cup, the presence of threads or rim design as well as material and surface texture.¹¹ Research suggests that threaded cups may offer greater initial stability compared to press-fit designs, particularly when measured by resistance to levering forces and micro-movements at the implant interface.^{12, 13, 14} However, despite these biomechanical advantages, the use of threaded cups remains under discussion due to inconsistencies in reported clinical outcomes.^{15, 16, 17}

Threaded cups have a rough surface with threads that provide initial stability by screwing into the prepared acetabulum.⁹ They offer high primary stability and precise implant positioning, but there are concerns about potential complications like acetabular fractures, bone resorption and osteolysis around the threads. They might require 1 mm over-reaming since the diameter of the prosthesis including the threads is larger than the body of the cup.^18,19 Inadequate preparation of the acetabulum rim may also lead to superficial placement. Press-fit cups, on the other hand, rely on an interference fit with the acetabulum for initial stability, which is then enhanced by bone ingrowth.⁷ They have shown equivalent clinical outcomes and osseous integration compared to threaded cups. The most common reasons for revision of cementless acetabular cups include aseptic loosening, osteolysis, and instability.^6,7 To achieve good long-term fixation, it is crucial to obtain a secure press-fit by carefully reaming the acetabulum to the appropriate size and ensuring adequate bone contact around the entire rim of the cup.^6,7 The use of additional screws with press-fit cups remains controversial, with some studies suggesting they are not necessary for stability. In summary, both threaded and press-fit cementless acetabular cups have been successfully used in total hip arthroplasty, with careful surgical technique being paramount to optimize fixation and minimize complications. The choice between the two types depends on surgeon preference and experience.^{6, 7, 8}

The purpose of the present systematic review with metanalysis was to compare the outcomes of TACs to PFACs in THA providing evidence-based data regarding their failure rates and radiological assessment.

2. Materials and methods

The primary objective of this systematic review and metanalysis was to offer a thorough compilation of current research pertaining to the utilization of PFACs compared to TACs in THA, by adhering to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.²⁰

This analysis took into account two principal factors: revision rates due to aseptic loosening and radiological evaluation (radiolucency/focal osteolysis). The study protocol has been registered with the PROSPERO international prospective register of systematic reviews (protocol number: CRD42023456104).

2.1. Search strategy and eligibility criteria

A meticulous online search of the PubMed and MEDLINE databases was conducted, until August 2023, to identify all articles reporting the outcome of TACs, compared to PFACs in THA. The following search strategy was used: (threaded) AND (hip), (total hip arthroplasty) AND (threaded), (threaded) AND (acetabular cup). In total, 751 articles were identified through the initial search. After duplicate removal, abstracts and titles of 460 articles were screened and 453 articles were excluded, as not congruent with the eligibility criteria. Seven eligible studies were identified, after full text screening and application of the inclusion/exclusion criteria, while the individual references listed in each publication were further investigated for ascertainment of additional studies. Search strategy is presented in Fig. 1.

Fig. 1.

Search strategy according to the PRISMA guidelines.

2.1.1. Inclusion criteria

• 1)Studies reporting prospective or retrospective comparative data between TACs and PFACs in THA.

2.1.2. Exclusion criteria

• 1)Studies not published in the English language
• 2)Studies presenting outcomes of either TAC or PFAC, without comparing these two types of components.
• 3)Expert opinions, book chapters or in-vitro investigations, as well as abstracts in scientific meetings.

2.2. Quality assessment of the studies

Two researchers (DK and CK) independently evaluated the quality of case-control studies included in the current metanalysis using the Newcastle-Ottawa scale (NOS).²¹ This scale employs a "star system" with a range of 0–9, with higher scores indicating better quality. The assessment is based on three key aspects: selection of study groups (4 questions), comparability of groups (1 question), and ascertainment of the outcome of interest (3 questions). Each question received a maximum of 1 star, except for the "comparability of the groups" aspect, where additional stars were granted for controlling data regarding aseptic loosening of the acetabular component and data regarding the radiological evaluation (maximum 2 stars). Discrepancies between the two investigators were resolved through reevaluation of the original article (Table 1).

Table 1.

Quality assessment of the studies using the Newcastle-Ottawa scale (NOS).

The Newcastle-Ottawa Scale	Is the case definition adequate?	Representativeness of the cases	Selection of controls	Definition of controls	Comparability of cases and controls on the basis of the design or analysis	Ascertainment of exposure	Same method for ascertainment for cases and controls	Non-response rate	Total *
Reikerås O, Gunderson RB, 2006	–	*	*	–	**	*	*	*	7
Manley MT, el al. 1998	–	*	*	–	**	*	*	*	7
Gala L et al., 2018	–	*	*	–	**	*	*	*	7
Ellenrieder M et al., 2016	–	*	*	–	*	*	*	–	5
Delaunay CP et al., 2016	–	*	*	–	**	*	*	*	7
Havelin LI et al., 1995	–	*	*	–	*	*	*	–	5
Müller U et al., 2003	–	*	*	–	*	*	*	–	5

2.3. Data extraction and synthesis

Data extraction was performed using a standardized data extraction form. The extracted data included study characteristics (author, year of publication, study design, sample size), participant demographics (gender and age), intervention details, outcome measures, and effect sizes. In the process of performing random-effect metanalysis, the generic inverse variance method was utilized to combine various studies that presented outcome estimates on different scales. To facilitate this combination, we calculated the natural logarithm of the odds ratios (ln (ORs)) and the corresponding standard errors (SE (ln (OR)). In cases where the studies did not provide the ORs and their respective confidence intervals (CIs), we derived these values by performing calculations using the original data.

Statistical analysis was conducted using ΙBM SPSS Statistics 29.0.1.0 software, and where applicable, a metanalysis was performed to estimate the overall effect size. Heterogeneity among the included studies was assessed, and sensitivity analyses were conducted to explore potential sources of heterogeneity. The analysis mostly employed the random effects model due to the presence of substantial heterogeneity among the individual studies.²² Metanalysis results were presented as a pooled proportion with 95 % CIs. Statistics were considered significant at a 0.05 probability level for all tests except heterogeneity, which was assessed with a p-value below 0.10.

2.4. Sensitivity analysis

Sensitivity analysis was conducted to assess the influence of excluding specific studies from the metanalysis, considering the weight assigned to each study, excluding studies with an OR equal to 1.00, and considering the outcomes of the critical evaluation of individual studies.

The aforementioned evaluation was based on the NOS. We made an arbitrary determination to exclude studies of poor or fair quality, setting a threshold of <6/9 as the limit for exclusion during the sensitivity analysis for risk of bias.

2.5. Subgroup analysis

In light of the significant heterogeneity observed among the studies, it was deemed necessary to perform a subgroup analysis into the three distinct subgroups, based on the type/generation of implants used in THA, the age and the gender of the participants. By conducting these subgroup analyses, a more detailed data examination was performed, allowing for deeper understanding of the factors influencing the outcomes of the metanalysis.

2.6. Publication bias risk assessment

In the absence of publication bias, the funnel plot resembled an inverted funnel, with smaller studies scattered widely at the bottom and larger studies clustering near the top.²³ The findings of Egger's test further supported the observation that there is no evidence of publication bias.²⁴

3. Results

The search strategy yielded a total of 751 articles, of which 7 met the inclusion criteria and were included in the statistical analysis.^{8,9,25, 26, 27, 28, 29}

3.1. Main findings

All included studies provided data regarding the exact number, gender and mean age of patients, except for one.²⁸ In total, 5457 patients (2149; 39.4 % males and 3308; 60/6 % females) were included in the present study, with mean age of 54.5 ± 9.6 years.^{8,9,25, 26, 27, 28}

All included studies reported the number of acetabular implants used in THAs and the mean period of follow up.^{8,9,25, 26, 27, 28, 29} In total, 14,561 THA were included, while a PFAC was used in 7877 (54.1 %) and a TAC in 6684 (45.9 %) cases. Concerning the PFACs, 5736 (72.8 %) were free of coating (1st generation) and 2141 (27.2 %) were coated (2nd or 3rd generation), while concerning the TACs, 3255 (48.7 %) were free of coating (1st generation) and 3429 (51.3 %) were coated (2nd or 3rd generation). The mean follow-up period was 7.6 ± 4.01 years. Table 2 summarizes the results of the metanalyses by the type of outcome.

Table 2.

Results of meta-analyses by type of outcome.

Outcome of interest	Number of studies	OR (95%CI)	Effect Model		Heterogeneity
				I2	P-value	Q-statistic
Revision due to aseptic loosening:
PFAC vs TAC	7	3.10 (0.37–25.72)	Random	92 %	0.29	59,20
PFAC vs TAC (sensitivity analysis after excluding large studies)	4	26.21 (3.49–196.01)	Random	59 %	<0.01	7.13
PFAC vs TAC (sensitivity analysis after excluding studies with OR = 1.00)	5	5.33 (0.27–105.27)	Random	95 %	0.27	55.47
PFAC vs TAC (sensitivity analysis after excluding low-quality studies)	4	1.02 (0.07–15.49)	Random	93 %	<0.01	28.44
2nd-3rd PFAC vs 2nd-3rd TAC	6	2.39 (0.29–30.66)	Random	91 %	0.37	47.84
PFAC vs TAC (subgroup analysis by age)	6	1.00 (0.06–16.14)	Random	93 %	1.00	55.69
PFAC vs TAC (subgroup analysis by gender)	6	3.99 (0.32–49.36)	Random	93 %	0.28	55.69
Radiological findings:
PFAC vs TAC	7	0.53 (0.26–1.08)	Random	69 %	<0.01	21.46
PFAC vs TAC (sensitivity analysis after excluding large studies)	4	0.67 (0.29–1.56)	Fixed	0 %	0.82	0.91
PFAC vs TAC (subgroup analysis by age)	6	0.47 (0.20–1.11)	Random	62 %	0.01	15.21
PFAC vs TAC (subgroup analysis by gender)	6	0.47 (0.20–1.11)	Random	62 %	0.01	15.21

3.2. Metanalysis: assessing the revision due to aseptic loosening

Regarding the implants utilized in THA, a total of 7 studies comprising 14,561 cases of THA from more than 8 different countries were included for quantitative evidence synthesis.

The initial metanalysis was conducted without considering the generation of the cups utilized in THA.

Due to substantial heterogeneity observed among the studies included (I² = 95.8 %, Cochrane Q test = 59.203, p-value <0.001), the random effects model was employed. The overall OR for revision due to aseptic loosening in THA with PFAC compared to TAC was 3.10 (95 % CI 0.37–25.72, p-value = 0.29). Among the included studies, two reported OR estimates of 1.00, three studies showed OR estimates above 1.00, and two studies demonstrated OR estimates below 1.00. Notably, 5 out of the 7 studies exhibited statistical significance (Fig. 2).

Fig. 2.

Forest plot demonstrating the summary odds ratio for total hip arthroplasty with press fit cups compared to threaded cups considering the revision due to aseptic loosening. Studies are listed in chronological order.

3.3. Sensitivity analysis

Through sensitivity analysis that considered the weight of each study, three studies conducted by Manley et al., Muller et al., and Reikeras et al. were removed as they carried the most significant weight in the metanalysis results.^{27, 28, 29} Following this exclusion, the metanalysis yielded a pooled odds ratio (OR) of 26.21 (95 % CI 3.49–196.91, p-value <0.001), indicating a significant association between using PFAC and a substantially better outcome in THA compared to TAC. The analysis also revealed low levels of heterogeneity (I² = 59 %, Cochrane Q test = 7.13, p-value = 0.007), suggesting that these studies played a crucial role in the overall results of the metanalysis and in the observed heterogeneity.

On the contrary, after excluding the studies by Muller et al. and Gala et al. with an OR equal to 1.00, the pooled OR was 5.33, although it did not demonstrate statistical significance (95 % CI 0.27–105.27, p-value = 0.27).^9,28

Conducting sensitivity analysis that exclusively incorporated studies (Manley et al., Reikeras et al., Delaunay et al., Gala et al.) deemed of good quality based on the NOS criteria did not lead to any alterations in the overall result pattern when estimating the combined treatment difference (pooled OR = 1.02, 95 % CI 0.07–15.49, p-value = 0.99) or in the degree of heterogeneity (I² = 93 %, Cochrane Q test = 28.44, p-value <0.001).^9,25,27,29

3.4. Subgroup analysis

3.4.1. By type/generation of arthroplasty cups

A subgroup analysis was performed, comprising studies that provided compatible data for the 2nd-3rd generation of PFAC and TAC. However, none of the components demonstrated statistically significant effects in reducing the risk of revision due to aseptic loosening in THA (OR = 2.39, 95 % CI 0.29–30.06, p-value = 0.37). Additionally, this analysis revealed notable heterogeneity among the included studies (I² = 91 %, Cochrane Q test p-value <0.001) (Fig. 3).

Fig. 3.

Forest plot demonstrating the summary odds ratio for aseptic loosening in total hip arthroplasty with 2nd-3rd generation press-fit cups compared to 2nd-3rd generation threaded cups. Studies are listed in chronological order.

3.4.2. By age

A sub-group analysis was performed by stratifying the data according to the age (mean years) of the patients in each study. The study by Muller et al. was excluded due to the absence of compatible data.²⁸ The analysis did not reveal any statistically significant subgroup effect (OR = 1.00, 95%CI 0.06–16.14, p-value = 1.00), while within-subgroup heterogeneity remained substantially high (I² = 93 %, Cochrane Q test p-value <0.001) (Fig. 4).

Fig. 4.

Forest plot demonstrating the summary odds ratio for revision due to aseptic loosening in total hip arthroplasty with press-fit cups compared to threaded cups according to the age subgroup analysis. Studies are listed in chronological order.

3.4.3. By gender

The study by Muller et al. was excluded due to the absence of compatible data.²⁸ The analysis revealed that females undergoing THA using PFAC, compared to TAC, had higher risk of revision due to aseptic loosening (OR = 5.26, 95 % CI 0.25–111.91), whereas the corresponding outcomes for males were approximately 2-fold lower (OR = 2.51, 95 % CI 0.01–1051.68). However, the gender did not have a significant subgroup effect (p-value = 0.29, 0.77 respectively), and within-subgroup heterogeneity remained high in all sub-groups (I² = 92.7 %, Cochrane Q test p-value <0.001) (Fig. 5).

Fig. 5.

Forest plot demonstrating the summary odds ratio for revision due to aseptic loosening in total hip arthroplasty with press-fit cups compared to threaded cups according to the gender subgroup analysis. Studies are listed in chronological order.

3.5. Publication bias

Upon inspection, the funnel plot of studies included in the primary analysis did not display significant signs of asymmetry, indicating a lack of substantial evidence for publication bias. This finding was further supported by statistical confirmation (Egger P = 0.250) (Fig. 6). Similarly, the visual inspection of the funnel plots of studies included in most of the subgroup analyses did not reveal any significant asymmetry suggestive of publication bias.

Fig. 6.

Funnel plot of the 7 studies included in the meta-analysis.

3.6. Metanalysis: assessing the radiological evaluations

A secondary metanalysis was conducted for radiological evaluation in THA comparing PFAC to TAC. Due to insufficient data in several of the included studies, the metanalysis was performed without considering the generation of cups.

Due to the significant heterogeneity observed between the included studies (I² = 69 %, Cochrane Q test = 21.46, p-value <0.001), the random effects model was applied. The overall OR for detecting radiolucency in THA with PFAC, when compared to TAC, was 0.53 (95%CI 0.26–1.08, p-value = 0.08). Of the 7 studies included, only one study exhibited statistically significant results²⁷ (Fig. 7).

Fig. 7.

Forest plot demonstrating the summary odds ratio for total hip arthroplasty with press-fit cups compared to threaded cups according to the radiological findings. Studies are listed in chronological order.

Unfortunately, it was not feasible to conduct a subgroup analysis based on the bone zone where radiolucency was detected due to insufficient data availability in most of the studies included.

3.7. Sensitivity analysis

By conducting a sensitivity analysis that took into account the relative weight of each study, three studies by Manley et al., Muller et al., and Gala et al. were excluded due to substantial influence on the metanalysis outcomes.^9,27,28 After this exclusion, the pooled odds ratio (OR) from the metanalysis was 0.67 (95 % CI 0.29–1.56, p-value = 0.035), indicating no significant disparity in radiological findings between the use of PFAC and TAC in THA. Interestingly, the analysis revealed minimal heterogeneity (I² = 0 %, Cochrane Q test = 0.91, p-value = 0.82), underscoring the pivotal role these studies played in shaping the overall results and observed heterogeneity of the metanalysis.

3.8. Sub-group analysis

3.8.1. By age

A sub-group analysis was executed by categorizing the data based on the mean age of patients in each study. The study conducted by Muller et al. was omitted due to the unavailability of compatible data.²⁸ The analysis did not uncover any statistically significant subgroup effect (OR = 0.47, 95 % CI 0.20–1.11, p-value = 0.08), while notable heterogeneity persisted within the subgroups (I² = 62 %, Cochrane Q test p-value = 0.01).

3.8.2. By gender

The study conducted by Muller et al. was removed due to the lack of suitable data.²⁸ The analysis indicated the absence of a statistically significant subgroup effect, while considerable within-subgroup heterogeneity persisted, as depicted in Fig. 8.

Fig. 8.

Forest plot demonstrating the summary odds ratio for radiolucency findings in total hip arthroplasty with press fit cups compared to threaded cups according to the gender subgroup analysis. Studies are listed in chronological order.

4. Discussion

In cementless designs of acetabular components in THA, primary implant fixation is achieved either by impaction of the prosthesis into the bone (PFAC) and possible screw insertion, or by mechanical interlocking of the prosthesis into the bone with threads (TAC). Primary stability provided by press fit design or by threads is necessary for the optimal clinical performance, while biological integration is the key contributing factor for favorable long-term results.^29,30 In the present systematic review with metanalysis, evidence-based data regarding the clinical outcomes and radiological evaluation of TACs and PFACs in THA is provided in a comparative way.

The present review included studies, that comparably provided information regarding 1st, 2nd and 3rd generation of PFAC and TAC. Based on the conducted metanalysis, that aimed at evaluating the revision rates due to aseptic loosening at mean follow-up of 7.6 ± 4.01 years, it can be deduced that PFAC did not exhibit superior outcomes in THA, compared to TAC, regardless of cup generation (OR: 3.10, 95 % confidence interval 0.37–25.72, p-value = 0.29). Notably, statistically significant association with favoring outcomes for PFAC over TAC was only observed upon the exclusion of studies, that carried the highest weight (OR: 26.21, 95 % CI 3.49–196.91, p-value <0.001).^{19, 20, 21}

Furthermore, the analysis unveiled, that females, faced higher risk of revision due to aseptic loosening when using PFAC over TAC, although this difference did not reach statistical significance. In particular, females undergoing THA, regardless cup design or generation, presented a 2-fold higher revision rate due to aseptic loosening, compared to males. Bone bed in females, especially in the elderly, can be of poor mechanical properties, as it very often suffers from metabolic diseases, such as osteoporosis.³¹ Furthermore, the present metanalysis revealed, that females undergoing THA with a PFAC had a 5-fold risk of revision (OR = 5.26, 95 % CI 0.25–111.91, p-value = 0.29) compared to females with TAC, regardless cup generation. These favorable results towards TAC might be attributed to the better initial mechanical interlocking of the threads of the implant to the female osteoporotic bone and might suggest that, TAC could be a possible alternative when subchondral bone is of dubious quality and does not provide adequate primary stability for a PFAC.

Apart from the type of prosthesis, patient related factors, like age and gender, have been frequently associated with clinical results. More specifically, THA in younger patients, regardless the cup design, has been related to higher revision rates.^27,29 This seems only natural, since human life expectancy tends to expand and human activity levels continually increase, while, at the same time, the components in THA wear down due to constant loading forces. According to the subgroup analysis, performed in the present study, none statistically significant effects in reducing the risk of revision due to aseptic loosening of PFAC versus TAC was demonstrated, regarding the 2nd and 3rd generation PFAC and TAC, or the age. Therefore, it may be assumed, that PFAC might be of better use in younger patients, since the revision incidence in this group is higher and the main concern for TAC during a revision surgery is the greater bone loss and possible removal difficulties, compared to PFAC.⁹

The presence of radiolucent lines around the acetabular prosthetic component of THA is considered to be a radiological sign of aseptic loosening of the cup and its incidence differs in regards to the diverse cup design.²⁸ Radiolucent lines are categorized in 3 zones and are a result of volumetric wear, implant biomechanics and biological activity of wear particles, suggesting the possibility of motion and distraction between the component and the underlying osseous structures and eventually the failure of fixation.^8,27 The follow up evaluation of radiolucencies around the cup might be of prognostic significance for the long-term results of THA. According to the present metanalysis, there was no significant difference in the incidence of radiolucent lines between the 2 components.

The present study has some limitations. The small number of available comparative studies, as well as the substantial heterogeneity of the included studies, regarding the cup generation, represents the main limitations. Furthermore, the present review includes studies, presenting both prospective and retrospective data, while not all of them presented sufficient data concerning the patients’ age and gender. However, the present study represents the first metanalysis in the literature, that compares the clinical outcomes and radiological evaluation of PFAC and TAC and offers invaluable insights regarding these acetabular cup designs and their use in THA.

5. Conclusions

The present systematic review with metanalysis compared the outcomes of PFAC and TAC in THA at 7.6 years follow up, providing valuable insights regarding their failure rates and radiological evaluation. The metanalysis showed, that women with PFAC in THA demonstrated higher rates of revision due to aseptic loosening of the cup, compared to TAC, although with no statistical significance. Furthermore, through sensitivity analysis, PFAC showed statistically significant superiority over TAC, regarding the clinical results, while after taking consideration all the included studies, PFAC showed similar results to TAC. Considering the radiological evaluation, both designs demonstrated similar results. Hence, PFACs remain the main option for THA, while TACs might be a viable alternative, especially in cases of bone of poor quality.

Credit author statement

Christos Koutserimpas: Conceptualization, Methodology, Writing- Original draft preparation. Dimitrios Kotzias: Data curation, Writing- Original draft preparation. Alexandra Argyrou: Visualization, Investigation. Enejd Veizi: Editing, Supervision.: Kalliopi Alpantaki & Athanasios Karamitros: Software, Validation.: Maria Piagkou: Writing- Reviewing, Editing, Supervision.