Impact of implant generation on the outcomes in medial pivot total knee arthroplasty: a systematic review

Filippo Migliorini; Marco Pilone; Luise Schäfer; Raju Vaishya; Michael Memminger; Nicola Maffulli

doi:10.1016/j.jor.2025.12.007

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73 (); 42-49

doi:

10.1016/j.jor.2025.12.007

Impact of implant generation on the outcomes in medial pivot total knee arthroplasty: a systematic review

Filippo Migliorini^a,b,c,d,, Marco Pilone^b, Luise Schäfer^d, Raju Vaishya^e, Michael Memminger^b, Nicola Maffulli^f,g,h

a Department of Trauma and Reconstructive Surgery, University Hospital of Halle, Martin-Luther University Halle-Wittenberg, 06097, Halle (Saale), Germany

b Department of Orthopaedic and Trauma Surgery, Academic Hospital of Bolzano (SABES-ASDAA), via Lorenz Böhler 5, 39100, Bolzano, Italy

c Department of Life Sciences, Health, and Health Professions, Link Campus University, Via del Casale di San Pio V, 00165, Rome, Italy

d Department of Orthopaedic and Trauma Surgery, Eifelklinik St.Brigida, Kammerbruschstr. 8, 52152, Simmerath, Germany

e Department of Orthopaedics and Joint Replacement Surgery, Indraprastha Apollo Hospital, Sarita Vihar, 110076, New Delhi, India

f Department of Trauma and Orthopaedic Surgery, Faculty of Medicine and Psychology, University “La Sapienza” of Rome, Via di Grottarossa 1035, 00189, Roma, Italy

g School of Pharmacy and Bioengineering, Keele University Faculty of Medicine, Stoke on Trent, ST4 7QB, United Kingdom

h Centre for Sports and Exercise Medicine, Queen Mary University of London, Barts and the London School of Medicine and Dentistry, Mile End Hospital, 275 Bancroft Road, E1 4DG, London, United Kingdom

⁎Corresponding author: Filippo Migliorini. filippo.migliorini@uk-halle.de

Received: 2025-11-12, Accepted: 2025-12-6, Published: 2025-12-8

The Authors

Disclaimer:
This article was originally published by Reed Elsevier India Pvt. Ltd. and was migrated to Scientific Scholar after the change of Publisher.

Abstract

Medial pivot total knee arthroplasty (TKA) was developed to reproduce native knee kinematics and improve function. Second-generation designs introduced refinements to enhance medial conformity and lateral rollback, but their clinical benefit remains uncertain. This systematic review compared outcomes of first- and second-generation medial pivot implants.

A comprehensive search of PubMed, Web of Science, Embase, and Google Scholar was performed in August 2025 following PRISMA guidelines. Comparative and non-comparative studies reporting outcomes after first- or second-generation medial pivot TKA were included. Primary endpoints were Knee Society Score (KSS), functional subscale (KSS-F), Oxford Knee Score (OKS), WOMAC, Forgotten Joint Score (FJS), range of motion (ROM), and revision rates.

Twenty-four studies including 4686 patients (3541 first-generation; 1145 s-generation) were analysed. Most baseline variables were comparable, though BMI, follow-up duration, and baseline WOMAC and ROM showed minor differences. At the latest follow-up, KSS, KSS-F, WOMAC, and FJS showed no significant differences. Revision rates were similar. OKS was slightly lower in the second-generation cohort (MD −2.5, p = 0.04), and ROM was greater (MD 4.6°, p = 0.01), but both fell below minimal clinically important difference thresholds.

First- and second-generation medial pivot TKAs achieved comparable outcomes and survivorship. Although second-generation designs showed statistical improvements in ROM and OKS, these were not clinically relevant. These findings suggest that while design refinements of second-generation implants may offer minor biomechanical advantages, they do not translate into significant improvements in patient-reported outcomes. Surgical decision-making should be based on the surgeon's experience, implant availability, and patient-specific factors rather than expectations of superior performance from newer designs.

Level III.

Keywords

Medial pivot arthroplasty

First generation

Second generation

Oxford knee score

Range of motion

Prosthesis design

Total knee arthroplasty

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1 Introduction

Medial pivot (MP) total knee arthroplasties (TKA) have been widely performed for over two decades, significantly improving function and quality of life in patients with debilitating knee osteoarthritis.¹^,² This prosthetic design was developed in the 1990s to replicate natural knee kinematics, particularly the characteristic femoral rollback during flexion, by positioning the centre of rotation in the medial compartment.³ First-generation MP implants operationalised this concept with a prominently conforming medial compartment intended to maintain a relatively fixed medial centre of rotation and to limit medial anteroposterior translation.⁴ The lateral compartment, by contrast, was relatively flat, allowing lateral motion, but within a geometry that was more constrained compared to later designs.⁵ These first-generation constructs demonstrated durable improvements in pain and function at mid-to long-term follow-up, supporting the feasibility and survivorship of the MP philosophy in routine clinical use.⁶^,⁷ Registry evidence further corroborates long-term performance of the first-generation MP design, reporting 10-year survivorship that meets or exceeds reference thresholds and is comparable with other cemented TKA systems.⁸

Second-generation MP systems refined the articular morphology to strengthen medial anteroposterior stability while purposefully permitting lateral rotational freedom, typically by pairing a near-spherical medial femoral geometry with a deep medial concavity and a flatter lateral surface, which encourages axial rotation with lateral rollback.^9–11 Second-generation MP TKAs have shown good functional outcomes and satisfactory mid-term survivorship in contemporary series and reviews.^12–16 To date, only one mid-term comparative study directly compares first- and second-generation MP TKAs.⁵ In that matched-cohort analysis, the second-generation design achieved greater postoperative knee flexion (ROM) and better functional scores than the first-generation implant.⁵ As personalised alignment strategies evolve and care becomes increasingly patient-specific, implant designs must likewise deliver knee kinematics that more closely replicate the native joint.¹⁷^,¹⁸

The objective of this systematic review is to evaluate the clinical and functional outcomes, as well as the revision rates, associated with mechanical complications of first- and second-generation MP TKA implants. By synthesising the available literature on both generations, we aim to determine whether second-generation designs are truly superior and to outline the kinematic rationale that can guide surgical decision-making toward prosthetic designs that more closely replicate native knee motion.

2 Methods

2.1

2.1 Eligibility criteria

All clinical studies comparing different generations of TKA implants with a medial pivot design were considered for inclusion. Articles published in English, German, French, Italian, or Spanish were eligible. Studies corresponding to Levels I to III of evidence, according to the Oxford Centre for Evidence-Based Medicine,¹⁹ were included. Non-comparative studies of Level IV were also eligible if they reported relevant clinical outcomes for at least one implant generation. Only studies with a minimum of 12 months of follow-up were included. Case reports, narrative or systematic reviews, expert opinions, editorials, letters, and studies based on animal models, cadaveric specimens, in vitro experiments, computer simulations, or purely biomechanical analyses were excluded. Studies without extractable clinical outcome data were not considered.

2.2

2.2 Search strategy

This systematic review was conducted according to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) 2020 guidelines.²⁰ The following predefined methodological framework was applied to guide the search and ensure methodological transparency:•Problem: end-stage knee osteoarthritis;•Intervention: medial pivot TKA;•Comparison: first vs second-generation of medial pivot implants;•Outcomes: functional scores, range of motion, complications, and revision rates.

In August 2025, a comprehensive electronic literature search was performed using PubMed, Web of Science, Google Scholar, and Embase. No restrictions on publication date were applied. The detailed search strings and Medical Subject Headings (MeSH) used for each database are provided in Table 1.

Table 1 Strings used in the databases.

Database	Search Strategy (MeSH terms and keywords)
PubMed	(“medial pivot” OR “medial stabilized” OR “medial congruent”) AND (“total knee arthroplasty” OR “total knee replacement”) AND (design OR generation OR “implant comparison” OR “prosthesis design” OR “implant evolution” OR Evolution)
Web of Science	ALL = (“medial pivot” AND “total knee arthroplasty”) AND (“implant generation” OR “design comparison” OR “first generation” OR “second generation” OR Evolution)
Google Scholar	“medial pivot” AND “total knee arthroplasty” AND (“first generation” OR “second generation” OR “implant evolution")
Embase	(‘medial pivot':ti,ab,kw OR ‘medial stabilized':ti,ab,kw) AND (‘total knee arthroplasty'/exp OR ‘total knee replacement’) AND (‘implant generation':ti,ab,kw OR ‘design comparison':ti,ab,kw OR ‘Evolution':ti,ab,kw)

2.3

2.3 Selection and data collection

Two authors (* and *.) independently performed the database search and screened all retrieved records for eligibility. Titles and abstracts were evaluated using predefined criteria. If relevance could not be confirmed based on the abstract, the full text was reviewed. Inaccessible full texts led to exclusion. To ensure completeness, the reference lists of all included full-text articles were manually screened for additional eligible studies. Any discrepancies during the selection process were resolved by discussion. A third reviewer (*) made the final decision if no agreement could be reached.

2.4

2.4 Data items

Two reviewers (* and *) independently performed data extraction. The following data at baseline were extracted: first author, year of publication, journal, study design, length of follow-up, number of patients with related mean age and BMI. Data concerning implant type and design generation, outcome measures, including Society Score (KSS), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), Forgotten Joint Score (FJS), Oxford Knee Score (OKS), Knee Injury and Osteoarthritis Outcome (KOOS), range of motion (ROM) and any complications or revisions were documented. All extracted data were organized using Microsoft Excel (version 16.0, Microsoft Corporation, Redmond, WA, USA).

2.5

2.5 Assessment of the risk of bias and quality of the recommendations

The risk of bias was assessed following the Cochrane Handbook for Systematic Reviews of Interventions guidelines.²¹ Two reviewers (* and *) independently evaluated the included studies. RCTs were appraised using the revised Risk of Bias assessment tool (RoB2)²²^,²³ of the Cochrane tool for assessing Risk of Bias in randomized trials (RoB) which evaluates five domains of potential bias: the randomization process, deviations from intended interventions, missing outcome data, measurement of outcomes, and selection of the reported results. Non-RCTs were evaluated using the Risk of Bias in Non-randomized Studies of Interventions (ROBINS-I) tool.²⁴ Seven domains of potential bias were assessed for non-randomized studies. Two domains addressed confounding and patient selection prior to the intervention. One domain evaluated misclassification during the intervention. The remaining four focused on post-intervention bias, including deviations from intended treatment, missing data, outcome measurement, and selective reporting. The ROBINS-I assessment was visualised using the Robvis Software (Risk-of-bias VISualization, Riskofbias.info, Bristol, UK).²⁵

2.6

2.6 Synthesis methods

Descriptive statistics were used to summarize the extracted data. Continuous variables, such as patient age or follow-up duration, were reported as arithmetic means and standard deviations. Dichotomous variables, such as the number of complications or reoperations, were presented as absolute frequencies (events/observations). The statistical analysis was performed by the main author (*) using IBM SPSS Statistics (version 25.0; IBM Corp., Armonk, NY, USA). The approach was based on the general recommendations of the Cochrane Handbook for Systematic Reviews of Interventions,²⁶ adapted to suit the qualitative nature of this review due to the heterogeneity of reported outcomes. For the analysis of the baseline comparability, the mean difference (MD) effect measure and the t-test were used. Values of P < 0.05 indicate statistically significant differences between groups in the baseline demographics. For the comparisons of the outcomes of interest at the last follow-up, the MD and the odds ratio (OR) effect measures were used for continuous and dichotomic data. Standard error was also calculated. The confidence interval was set at 95 % in all comparisons. Values of P < 0.05 were considered statistically significant.

3 Results

3.1

3.1 Study selection

The database search identified a total of 251 records. After the removal of 112 duplicates, 139 records remained for screening. Titles and abstracts were reviewed, resulting in the exclusion of 83 studies. The main reasons for exclusion were study design (N = 9), level of evidence (n = 13), not meeting the predefined inclusion criteria (n = 12), lack of clear information on implant generation or design in medial pivot TKA (n = 21), insufficient reporting of clinical outcomes (n = 15), and language restrictions (n = 13). Twenty-six further studies were excluded after full-text review because no quantitative outcome data were available. A total of 30 studies met all inclusion criteria and were included in the analysis, comprising four RCTs, three prospective and 23 retrospective comparative studies and non-comparative investigations. The study selection process is illustrated in Fig. 1.

PRISMA flow chart of the literature search.

3.2

3.2 Methodological quality assessment

Four RCTs were assessed using the revised Risk of Bias assessment tool (RoB2).²²^,²³ All studies showed low risk of bias in the randomization process, with transparent allocation and no evidence of baseline imbalances. Deviations from intended interventions were minimal across studies, with only one trial raising some concerns in this domain. All studies reported complete outcome data, and outcome measurement was judged appropriate in most cases. The risk of bias because of selective reporting was low in three trials and rated as “some concerns” in one. In conclusion, all included RCTs were judged to have a low overall risk of bias, supporting the reliability of their findings (Fig. 2).

Twenty-seven studies were assessed using the ROBINS-I tool for non-randomized designs.²⁵ Confounding represented the most critical source of bias, consistently rated as moderate, reflecting typical limitations of retrospective comparisons without adequate control for patient selection or surgical variables. In contrast, the risk of bias related to participant selection and intervention classification was low across most studies, with clearly defined groups and consistent documentation. Follow-up completeness and handling of missing data were also rated favorably. Outcome assessment posed a recurring concern because of subjective scores and lack of blinding, leading to a moderate risk in this domain. However, all studies reported outcomes transparently, with no signs of selective reporting. Despite confounding and outcome measurement limitations, the included studies were judged to have a low overall risk of bias, supporting acceptable internal validity within the constraints of non-randomized evidence (Fig. 3).

3.3

3.3 Study characteristics and results of individual studies

A total of 4686 patients were included in the present analysis, with 3541 receiving a first-generation and 1145 a second-generation medial pivot implant. 20 % (937 of 4686) of the patients were male. The mean age across all cohorts was 69.9 ± 4.5 years, and the mean BMI was 28.5 ± 2.5 kg/m². The follow-up duration varied considerably across studies, with a mean of 61.3 ± 52.6 months. An overview of the baseline characteristics is provided in Table 2.

Table 2 Generalities and patient characteristics (LoE: level of Evidence; BMI: body mass index).

Author	Journal	LoE	Follow-up (month)	Patients (n)	Male (n)	Age (mean)	BMI (kg/m²)	Generation
Bae et al., 2011⁹	JOA	III	47	67	1	67.5	26.0	1st
Bae et al., 2011⁹	JOA	III	47	70	6	65.8	26.7	1st
Batra et al., 2022²⁷	CiOS	IV	60	45	5	61.7	28.4	1st
Chinzei et al., 2023²⁸	The Knee	IV	93	85	5	70.2	26.5	1st
Choi et al., 2017²⁹	JOA	III	60	49	6	66.7	27.6	1st
Delman et al., 2023³⁰	KSSTA	III	19	25	12	70.0	29.0	2nd
Elorza et al., 2023 a³¹	International Orthopaedics	III	15	25		67.0	30.8	2nd
Elorza et al., 2023 b³²	The Knee	III	19	25	12	71.0	29.0	2nd
Ettinger et al., 2024³³	KSSTA	II	48	47	38	68.8	28.1	2nd
Ettinger et al., 2024³³	KSSTA	II	48	51	40	63.1	29.0	2nd
Fan et al., 2010¹	JOA	IV	65	59	13	65.1	–	1st
Howel et al., 2025³⁴	KSSTA	III	24	117	52	68.0	30.0	2nd
Hu et al., 2023³⁵	Heliyon	III	103	84	–	68.2	27.9	1st
Hu et al., 2023³⁵	Heliyon	III	105	168	–	67.5	28.1	1st
Ishida et al., 2014³⁶	KSSTA	II	57	71	14	71.0	27.2	1st
Jeremìc et al., 2020³⁷	OTSR	III	12	24	–	70.7	30.6	2nd
Jeremìc et al., 2020³⁷	OTSR	III	12	24	–	82.5	30.0	2nd
Kage et al., 2024³⁸	J. Of experimental Orthopaedic	III	12	19	4	74.7	25.5	2nd
Kage et al., 2024³⁸	J. Of experimental Orthopaedic	III	12	19	5	77.2	26.2	2nd
Karachalios et al., 2016⁶	BJJ	IV	161	225	41	71.0	33.0	1st
Karachalios et al., 2021³⁹	JOA	III	180	100	31	63.2	32.0	1st
Karahan et al., 2023¹³	Acta Orthop Belg	III	79	227	40	66.6	–	2nd
Karahan et al., 2023¹³	Acta Orthop Belg	III	79	77	13	66.6	–	2nd
Koutp et al., 2025⁴⁰	KSSTA	I	24	50	30	69.6	31.5	2nd
Koutp et al., 2025⁴⁰	KSSTA	I	24	50	29	72.5	30.0	2nd
Macheras et al., 2017⁷	The Knee	III	182	176	60	73.0	28.9	1st
Macheras et al., 2017⁷	The Knee	III	182	149	50	80.0	30.1	1st
Niesen et al., 2024⁴¹	Acta Orthop	III	12	35	19	67.0	31.0	2nd
Niesen et al., 2024⁴¹	Acta Orthop	III	12	35	21	68.0	31.0	2nd
Obada et al., 2025⁴²	International Orthopaedics	I	24	300	–	68.4	28.5	1st
Risitano et al., 2020⁴³	JEO	IV	12	15	7	–	–	2nd
Sosio et al., 2023³	JCM	IV	24	55	23	71.5	29.3	2nd
Ueyama et al., 2023⁴⁴	Arthroplasty	IV	142	96	6	70.2	27.2	1st
Ueyama et al., 2022 a⁵	AOTS	III	107	153	18	77.0	23.0	1st
Ueyama et al., 2022 a⁵	AOTS	III	107	153	23	76.0	24.0	2nd
Ueyama et al., 2022 b⁴⁵	JOA	III	120	257	17	76.2	23.4	1st
Ueyama et al., 2022 b⁴⁵	JOA	III	120	77	10	74.6	23.3	1st
Vecchini et al., 2012⁴⁶	The Knee	IV	84	160	42	71.0	–	1st
Xiang et al., 2021⁴⁷	International Orthopaedics	IV	60	1070	193	67.2	27.7	1st
Youm et al., 2014⁴	Knee Surgery and Related Research	III	65	80	9	66.4	–	1st

3.4

3.4 Baseline comparability

The two cohorts were comparable in age (p = 0.6). A statistically significant difference was observed in sex distribution (p < 0.001), with the second-generation cohort including a greater proportion of men. BMI was also significantly higher in the second-generation group (p = 0.016). Follow-up duration was longer in the first-generation group (p < 0.001). At baseline, the two cohorts were comparable in KSS (p = 0.1), KSS-F (p = 0.7), and OKS (p = 0.3). A statistically significant difference was observed in WOMAC, which was higher in the first-generation group (p = 0.04). Baseline ROM was significantly greater in the second-generation cohort (p < 0.001). These results are shown in Table 3.

Table 3 Baseline comparability (BMI: body mass index; KSS: Knee Society Score; KSS-F: KSS functional subscale; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index; OKS: Oxford Knee Score; ROM: Range of Motion).

Endpoint	I generation	II generation	P
Male (%)	12.7 ± 11.1	39.0 ± 25.5	0.000
Age (years)	69.6 ± 4.5	70.3 ± 4.6	0.6
BMI (kg/m²)	27.6 ± 2.5	29.4 ± 1.7	0.02
Follow-up (months)	98.7 ± 46.2	27.1 ± 22.0	0.000
KSS	36.3 ± 10.7	42.9 ± 10.2	0.1
KSS-F	40.7 ± 8.3	42.0 ± 8.1	0.7
WOMAC	68.1 ± 8.7	56.7 ± 7.0	0.04
OKS	21.3 ± 6.1	24.2 ± 3.8	0.3
ROM (°)	101.2 ± 13.9	116.3 ± 3.7	0.000

4 Results syntheses

At the final follow-up, no significant differences were observed in KSS (MD −1.3; p = 0.585), KSS-F (MD −0.1; p = 0.976), or WOMAC (MD 0.4; p = 0.918). The second-generation cohort evidenced lower FJS (MD −6.1; p = 0.092) and Oxford scores (MD −2.5; p = 0.014). Revision rates were lower in the second-generation group (OR 0.65; p = 0.370). These results are reported in Table 4.

Table 4 Result syntheses (KSS: Knee Society Score; KSS-F: KSS functional subscale; WOMAC: Western Ontario and McMaster Universities Osteoarthritis Index; FJS: Forgotten Joint Score; OKS: Oxford Knee Score; ROM: Range of Motion; SE: Standard Deviation; CI: Confidence Interval).

Endpoint	I generation	II generation	SE	95 % CI	Effect size	P
KSS	88.4 ± 4.2	87.2 ± 5.8	2.23	−5.6, 3.1	MD -1.3	0.6
KSS-F	79.2 ± 7.9	79.1 ± 12.3	3.91	−7.8, 7.6	MD -0.1	0.9
WOMAC	15.7 ± 4.8	16.1 ± 8.4	4.16	−7.7, 8.6	MD 0.4	0.9
FJS	76.4 ± 4.6	70.3 ± 10.3	3.42	−12.8, 0.6	MD -6.1	0.09
OKS	44.3 ± 0.4	41.8 ± 3.2	0.89	−4.3, −0.8	MD -2.5	0.01
ROM (°)	114.0 ± 6.7	118.7 ± 5.9	2.24	0.2, 9.0	MD 4.6	0.05
Revisions (n/N (%))	13/3793 (0.3)	2/917 (0.2)	–	–	OR 0.64	0.04

5 Discussion

The present systematic review compared first- and second-generation medial pivot total knee arthroplasty implants across 4686 patients, of whom 3541 received a first-generation device and 1145 received a second-generation device. At baseline, the two groups were broadly comparable in terms of age. However, differences were observed in sex distribution BMI, follow-up duration, baseline WOMAC scores, and ROM. Importantly, the OKS was comparable at baseline. At the final follow-up, no statistically significant differences were detected in the KSS or its functional subscale, in the WOMAC, or in the FJS. Revision rates were similar, with an odds ratio of 0.64, but a P-value above the threshold of significance. The only two outcomes that reached statistical significance were the OKS, which was lower in the second-generation group with a mean difference of −2.5 points, and the ROM, which was slightly higher in the second-generation cohort with a mean difference of 4.6°. Both differences, although statistically significant, remain below clinically meaningful thresholds. The MCID for the OKSin primary total knee arthroplasty is approximately 5 points, as demonstrated by Clement et al.⁴⁸ in a prospective study involving more than 500 patients, and subsequently confirmed by further analyses. Thus, the observed −2.5 point difference between first- and second-generation implants, although statistically significant, falls short of clinical relevance.⁴⁸ A similar reasoning applies to ROM, for which the MCID has been estimated between 3.8 and 6.4° in patients with knee osteoarthritis. The 4.6° advantage observed for second-generation implants falls within this range, suggesting a change that could be perceptible to patients. However, the lower boundary of the MCID interval indicates that this difference may not always translate into consistent functional benefit.

The interpretation of these findings requires consideration of implant design evolution, clinical thresholds of meaningful improvement, and biomechanical plausibility. First generation medial pivot implants introduced the principle of a highly conforming medial compartment with a relatively fixed centre of rotation and a flatter lateral compartment, providing intrinsic anteroposterior stability medially and controlled translation laterally.⁴²^,⁴⁹^,⁵⁰ These designs demonstrated durable improvements in function and survivorship over more than a decade of follow-up, supporting the validity of the medial pivot concept.⁸^,⁵¹^,⁵² Second-generation designs refined this philosophy by enhancing medial conformity and permitting greater lateral rollback and axial rotation, attempting to reproduce more faithfully the screw home mechanism and the asymmetric motion of the native knee.⁵³^,⁵⁴ From a biomechanical perspective, the small but significant increase in range of motion observed with second-generation devices is consistent with these refinements.⁵⁵ Fluoroscopic and in vivo kinematic studies have demonstrated that medial pivot designs with a spherical medial geometry and permissive lateral conformity can more accurately reproduce native femoral rollback than earlier iterations, thereby facilitating deeper flexion without compromising medial stability.⁵⁶^,⁵⁷ The observed 4.6° difference, while modest, aligns with these mechanistic expectations. Clinically, however, whether such an increase leads to perceivable differences in activities of daily living is uncertain, as most functional tasks are achievable with 110 degrees of flexion, and higher arcs may only benefit demanding activities such as kneeling or squatting.

The difference in the OKS is more difficult to interpret. A possible explanation lies in the distribution of baseline characteristics, as patients receiving second-generation implants had a higher BMI and shorter follow-up, both of which may negatively influence patient-reported outcomes. Another factor may be the learning curve and adoption period associated with newer designs, which could affect soft tissue balancing and component positioning.⁵⁸^,⁵⁹ From a biological standpoint, both first and second generation implants rely on similar materials, fixation methods and polyethylene formulations, suggesting that differences in outcome are unlikely to stem from implant biology.⁶⁰^,⁶¹ Instead, the observed OKS discrepancy may reflect a statistical artefact amplified by heterogeneity in study design, rather than a true inferiority of the second-generation design.

Overall, the lack of meaningful differences between generations suggests that the fundamental medial pivot concept is robust and effective in both iterations. The refinements of second-generation implants may yield biomechanical advantages such as slightly greater flexion and more natural kinematics, but these did not translate into clinically relevant superiority in patient-reported outcomes or survivorship within the available follow-up. The apparent statistical significance of the OKS must be tempered by the recognition that the difference lies below the accepted MCID, and therefore cannot be considered of practical importance to patients. Likewise, the range of motion advantage, while within the MCID interval, represents only a marginal functional gain that may not affect quality of life for most patients.

Single-centre observational cohorts dominate most evidence, so selection bias, centre effects, and residual confounding by indication remain credible despite conventional adjustments. Focusing the analysis on two medial-pivot systems (MicroPort ADVANCE, first generation, and Medacta GMK Sphere, second generation) reduces product heterogeneity. Still, it makes “generation” inseparable from “manufacturer,” limiting generalizability beyond these brands. Operative execution and peri-operative care were variably reported: alignment philosophy (MA versus KA), balancing strategy (measured resection versus gap-balancing), tibial slope targets, thresholds for soft-tissue release, patellar resurfacing policy, anaesthetic/analgesic pathways, and rehabilitation protocols differed among centres and eras; each can influence stability, patellofemoral tracking, pain, and function independent of implant generation. Follow-up horizons were heterogeneous and tended to be longer in ADVANCE cohorts than in Sphere cohorts, increasing the chance of capturing late wear or loosening in the former while underpowering detection of rare failure modes in the latter, thereby complicating survivorship comparisons and time-to-event synthesis. Outcome ascertainment was non-uniform, and definitions of instability, stiffness, and patellofemoral complications were not standardised. Finally, revisions were intentionally limited to mechanical causes (aseptic loosening and revision for instability) to appraise implant mechanics; septic and traumatic indications were excluded by design, yielding cause-specific rather than all-cause estimates. Given these constraints, the pooled estimates should be interpreted with caution and not as definitive evidence of generational superiority. Stronger inferences will require pre-registered, adequately powered, multicentre head-to-head studies with standardised surgical protocols; explicit radiographic verification of achieved alignment and component orientation; balanced long-term follow-up with competing-risk time-to-event analyses; RSA migration sub-studies; stratification by alignment strategy and PCL management; detailed reporting of polyethylene formulation, insert constraint, and fixation; harmonised PROMs with MCID thresholds and blinded assessment.

6 Conclusion

Both first and second-generation medial pivot total knee arthroplasty implants provide reliable improvements in function, patient-reported outcomes, and survivorship. Although second-generation devices achieved statistically greater range of motion and first-generation devices achieved slightly better OKS, neither difference exceeded the minimal clinically important difference. These results indicate that the refinements introduced in second-generation implants, while biomechanically plausible, do not translate into meaningful advantages for patients. Therefore, both designs can be considered safe and effective, and implant selection should be guided by patient characteristics, intraoperative findings, and surgeon preference rather than by expectations of significant clinical superiority of one generation over the other.

Author contribution statement

FM: literature search, data extraction, risk of bias assessment, conception and design, drafting; RV, MM: supervision, revision; FM, MP: writing; LS, NM: literature search, data extraction, risk of bias assessment; NM: supervision. All authors have agreed to the final version to be published and agree to be accountable for all aspects of the work.

Ethical approval

This study complies with ethical standards.

Registration and protocol

The present review was not registered.

Availability of data and materials

The datasets generated during and/or analysed during the current study are available throughout the manuscript.

Ethical statement

This article does not contain any studies with human participants or animals performed by any of the authors. Ethical approval was therefore not required.

Funding statement

The authors received no financial support for the research, authorship, and/or publication of this article.

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Youm Y.S., Cho S.D., Lee S.H., Cho H.Y., . Total knee arthroplasty using a posterior cruciate ligament sacrificing medial pivot knee: minimum 5-year Follow-up results. Knee Surg Relat Res. 2014;26(3):135-140.
[Google Scholar]
Ueyama H., Kanemoto N., Minoda Y., Yamamoto N., Taniguchi Y., Nakamura H., . Comparison of postoperative knee flexion and patient satisfaction between newly and conventionally designed medial pivot total knee arthroplasty: a 5-year follow-up matched cohort study. Arch Orthop Trauma Surg. 2022;142(8):2057-2064.
[Google Scholar]
Karachalios T., Varitimidis S., Bargiotas K., Hantes M., Roidis N., Malizos K.N., . An 11- to 15-year clinical outcome study of the Advance Medial Pivot total knee arthroplasty: pivot knee arthroplasty. Bone Joint Lett J. 2016;98-B(8):1050-1055.
[Google Scholar]
Macheras G.A., Galanakos S.P., Lepetsos P., Anastasopoulos P.P., Papadakis S.A., . A long term clinical outcome of the Medial Pivot Knee Arthroplasty System. Knee. 2017;24(2):447-453.
[Google Scholar]
Bordini B., Ancarani C., Fitch D.A., . Long-term survivorship of a medial-pivot total knee system compared with other cemented designs in an arthroplasty registry. J Orthop Surg Res. 2016;11:44.
[Google Scholar]
Bae D.K., Song S.J., Cho S.D., . Clinical outcome of total knee arthroplasty with medial pivot prosthesis a comparative study between the cruciate retaining and sacrificing. J Arthroplast. 2011;26(5):693-698.
[Google Scholar]
Schutz P., Taylor W.R., Postolka B., et al . Kinematic evaluation of the GMK sphere implant during gait activities: a dynamic videofluoroscopy Study. J Orthop Res. 2019;37(11):2337-2347.
[Google Scholar]
Scott G., Imam M.A., Eifert A., et al . Can a total knee arthroplasty be both rotationally unconstrained and anteroposteriorly stabilised? A pulsed fluoroscopic investigation. Bone Joint Res. 2016;5(3):80-86.
[Google Scholar]
Bauer L., Woiczinski M., Thorwachter C., et al . Influence of kinematic alignment on femorotibial kinematics in medial stabilized TKA design compared to mechanical alignment. Arch Orthop Trauma Surg. 2023;143(7):4339-4347.
[Google Scholar]
Karahan M., Acar E., Serarslan U., Gultekin A., . Medial pivot total knee arthroplasty: Mid-term results. Acta Orthop Belg. 2023;89(1):97-102.
[Google Scholar]
Katchky A.M., Jones C.W., Walter W.L., Shimmin A.J., . Medial ball and socket total knee arthroplasty: five-year clinical results. Bone Joint Lett J. 2019;101-B(1_Supple_A):59-65.
[Google Scholar]
Ohrn F.D., Gothesen O., Lastad Lygre S.H., et al . Decreased survival of medial pivot designs compared with cruciate-retaining designs in TKA without patellar resurfacing. Clin Orthop Relat Res. 2020;478(6):1207-1218.
[Google Scholar]
Razick D., Akhtar M., Howell S.M., Nedopil A.J., Hull M.L., . The location of the centre of the proximal quadriceps tendon in kinematically aligned total knee arthroplasty is not associated with poor outcome scores or symptomatic patellar instability. J Exp Orthop. 2024;11(4)
[Google Scholar]
Migliorini F., Maffulli N., Pilone M., et al . Mechanical versus kinematic alignment for total knee arthroplasty: a meta-analysis. Arch Orthop Trauma Surg. 2025;145(1):212.
[Google Scholar]
Migliorini F., Pilone M., Schafer L., Simeone F., Bell A., Maffulli N., . Functional alignment in robotic-assisted total knee arthroplasty: a systematic review. Arch Orthop Trauma Surg. 2024;144(4):1741-1749.
[Google Scholar]
Howick J.C.I., Glasziou P., Greenhalgh T., et al . The 2011 Oxford CEBM Levels of Evidence. 2011
[Google Scholar]
Page M.J., McKenzie J.E., Bossuyt P.M., et al . The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. Br Med J. 2021;372
[Google Scholar]
2022
[Google Scholar]
Sterne J.A.C., Savovic J., Page M.J., et al . RoB 2: a revised tool for assessing risk of bias in randomised trials. Br Med J. 2019;366
[Google Scholar]
Higgins J.P.T.S.J., Page M.J., Elbers R.G., Sterne J.A.C., . Chapter 8: assessing risk of bias in a randomized trial. 2022
[Google Scholar]
Sterne J.A., Hernan M.A., Reeves B.C., et al . ROBINS-I: a tool for assessing risk of bias in non-randomised studies of interventions. Br Med J. 2016;355
[Google Scholar]
McGuinness L.A., Higgins J.P.T., . Risk-of-bias VISualization (robvis): an R package and shiny web app for visualizing risk-of-bias assessments. Research Synthesis Methods n/a (n/a) 2020
[Google Scholar]
Higgins J.P.T.T.J., Chandler J., Cumpston M., Li T., Page M.J., Welch V.A., . Cochrane Handbook for Systematic Reviews of Interventions Version 6.2. 2021
[Google Scholar]
Batra S., Malhotra R., . Medial ball and socket total knee arthroplasty in Indian population: 5-Year clinical results. Clin Orthop Surg. 2022;14(1):90-95.
[Google Scholar]
Chinzei N., Ishida K., Tsumura N., et al . Satisfactory results at 8 years mean follow-up after ADVANCE(R) medial-pivot total knee arthroplasty. Knee. 2014;21(2):387-390.
[Google Scholar]
Choi N.Y., Y , Bae J.H., Do J.H., Chung S.J., Koh I.J., . Are midterm patient-reported outcome measures between rotating-platform mobile-bearing prosthesis and medial-pivot prosthesis different? A minimum of 5-Year Follow-Up Study. J Arthroplast. 2017;32(3):824-829.
[Google Scholar]
Delman C.M., Ridenour D., Howell S.M., Hull M.L., . The posterolateral upslope of a low-conforming insert blocks the medial pivot during a deep knee bend in TKA: a comparative analysis of two implants with different insert conformities. Knee Surg Sports Traumatol Arthrosc. 2023;31(9):3627-3636.
[Google Scholar]
Elorza S.P., O'Donnell E., Nedopil A., Howell S.M., Hull M.L., . Ball-in-socket medial conformity with posterior cruciate ligament retention neither limits internal tibial rotation and knee flexion nor lowers clinical outcome scores after unrestricted kinematically aligned total knee arthroplasty. Int Orthop. 2023;47(7):1737-1746.
[Google Scholar]
Pacheco Elorza S., O'Donnell E., Delman C., Howell S.M., Hull M.L., . Posterior cruciate ligament retention with medial ball-in-socket conformity promotes internal tibial rotation and knee flexion while providing high clinical outcome scores. Knee. 2023;43:153-162.
[Google Scholar]
Ettinger M., Tuecking L.R., Savov P., Windhagen H., . Higher satisfaction and function scores in restricted kinematic alignment versus mechanical alignment with medial pivot design total knee arthroplasty: a prospective randomised controlled trial. Knee Surg Sports Traumatol Arthrosc. 2024;32(5):1275-1286.
[Google Scholar]
Howell S.M., Zabiba A., Nedopil A.J., Hull M.L., . The Forgotten Joint Score after total knee arthroplasty with a kinematic alignment-optimized femoral component matches total hip arthroplasty. Knee Surg Sports Traumatol Arthrosc 2025
[Google Scholar]
Hu M., Xiang S., Xu H., Wang Y., Lv C., Zhang H., . Equivalence of clinical and radiological outcomes in cruciate-retaining and cruciate-substituting total knee arthroplasty with medial pivot knee: a comparative study. Heliyon. 2023;9(12)
[Google Scholar]
Ishida K., Matsumoto T., Tsumura N., et al . No difference between double-high insert and medial-pivot insert in TKA. Knee Surg Sports Traumatol Arthrosc. 2014;22(3):576-580.
[Google Scholar]
Jeremic D.V., Massouh W.M., Sivaloganathan S., Rosali A.R., Haaker R.G., Riviere C., . Short-term follow-up of kinematically vs. mechanically aligned total knee arthroplasty with medial pivot components: a case-control study. Orthop Traumatol Surg Res. 2020;106(5):921-927.
[Google Scholar]
Kage T., Kono K., Tomita T., et al . Medial pivot total knee arthroplasty for valgus knees provides equivalent medial stability compared to that for varus knees: in vivo kinematic study. J Exp Orthop. 2024;11(4)
[Google Scholar]
Karachalios T., Komnos G., Hantes M., Varitimidis S., . Evaluating the "Patella-Friendly" concept in total knee arthroplasty: a minimum 15-Year Follow-Up outcome Study comparing constant radius, Multiradius Cruciate-Retaining, and nonanatomical cruciate-retaining implants. J Arthroplast. 2021;36(8):2771-2778.
[Google Scholar]
Koutp A., Schroedter R., Leitner L., Vielgut I., Leithner A., Sadoghi P., . Unrestricted kinematic alignment offers limited functional benefit over mechanical alignment in medial pivot total knee arthroplasty: a randomized controlled trial using conventional instrumentation. Knee Surg Sports Traumatol Arthrosc 2025
[Google Scholar]
Niesen A.E., Tirumalai P.A., Howell S.M., Hull M.L., . A new tibial insert design with ball-in-socket medial conformity and posterior cruciate ligament retention has low tibial baseplate migration after unrestricted kinematically aligned total knee arthroplasty: a cohort study using radiostereometric analysis. Acta Orthop. 2024;95:758-764.
[Google Scholar]
Obada B., Iliescu M.G., Costea D.O., Petcu L., Popescu A.I., . Comparative study of outcomes with total knee arthroplasty: medial pivot prosthesis vs posterior stabilized implant. Prospective randomized control. Int Orthop. 2025;49(3):629-639.
[Google Scholar]
Risitano S., Sabatini L., Barberis L., Fusini F., Malavolta M., Indelli P.F., . Combining kinematic alignment and medial stabilized design in total knee arthroplasty: basic rationale and preliminary clinical evidences. J Orthop. 2020;21:427-431.
[Google Scholar]
Ueyama H., Nakagawa S., Kishimura Y., et al . Long-term clinical results of alumina ceramic medial pivot total knee arthroplasty: a 10-year follow-up study. Arthroplasty. 2023;5(1):27.
[Google Scholar]
Ueyama H., Kanemoto N., Minoda Y., Yamamoto N., Taniguchi Y., Nakamura H., . No difference in postoperative knee flexion and patient joint awareness between cruciate-substituting and cruciate-retaining medial pivot total knee prostheses: a 10-Year Follow-Up Study. J Arthroplast. 2022;37(2):279-285.
[Google Scholar]
Vecchini E., Christodoulidis A., Magnan B., Ricci M., Regis D., Bartolozzi P., . Clinical and radiologic outcomes of total knee arthroplasty using the advance Medial Pivot prosthesis. A mean 7 years follow-up. Knee. 2012;19(6):851-855.
[Google Scholar]
Xiang S., Wang Y., Lv C., Wang C., Zhang H., . Mid-term clinical outcomes and survivorship of medial-pivot total knee arthroplasty-a mean five year follow-up based on one thousand, one hundred and twenty eight cases. Int Orthop. 2021;45(11):2877-2883.
[Google Scholar]
Clement N.D., MacDonald D., Simpson A.H., . The minimal clinically important difference in the Oxford knee score and Short Form 12 score after total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2014;22(8):1933-1939.
[Google Scholar]
Brendle S.A., Krueger S., Grifka J., et al . Constraint of different knee implant designs under anterior-posterior shear forces and internal-external rotation moments in human cadaveric knees. Bioengineering (Basel). 2025;12(1)
[Google Scholar]
Hamilton L.D., Shelburne K.B., Rullkoetter P.J., Barnes C.L., Mannen E.M., . Kinematic performance of medial pivot total knee arthroplasty. J Arthroplast. 2024;39(6):1595-1601 e1597.
[Google Scholar]
Hodgeson S.M., Soeno T., Mears S.C., Stambough J.B., Barnes C.L., Stronach B.M., . The medial pivot design in total knee arthroplasty. Orthop Clin North Am. 2024;55(1):49-59.
[Google Scholar]
Freeman M.A., Pinskerova V., . The movement of the knee studied by magnetic resonance imaging. Clin Orthop Relat Res. 2003;410:35-43.
[Google Scholar]
Christen B., Kopjar B., . Second-generation bi-cruciate stabilized total knee system has a lower reoperation and revision rate than its predecessor. Arch Orthop Trauma Surg. 2018;138(11):1591-1599.
[Google Scholar]
La Verde M., Belvedere C., Cammisa E., et al . Mechanically aligned second-generation medial pivot primary total knee arthroplasty does not reproduce normal knee biomechanics: a gait analysis Study. J Clin Med. 2024;13(18)
[Google Scholar]
Dabirrahmani D., Farshidfar S., Cadman J., et al . Biomechanical improvements in gait following medial pivot knee implant surgery. Clin Biomech. 2024;116
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Heyse T.J., Slane J., Peersman G., et al . Kinematics of a bicruciate-retaining total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2017;25(6):1784-1791.
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Show Sections

[1] Fan C.Y., Hsieh J.T., Hsieh M.S., Shih Y.C., Lee C.H., . Primitive results after medial-pivot knee arthroplasties: a minimum 5-year follow-up study. J Arthroplast. 2010;25(3):492-496.
[Google Scholar]

[2] Shi W., Jiang Y., Wang Y., Zhao X., Yu T., Li T., . Medial pivot prosthesis has a better functional score and lower complication rate than posterior-stabilized prosthesis: a systematic review and meta-analysis. J Orthop Surg Res. 2022;17(1):395.
[Google Scholar]

[3] Sosio C., Rossi N., Sirtori P., et al . Clinical and functional outcomes of kinematic aligned total knee arthroplasty with a medial pivot design: Two-Year Follow-Up. J Clin Med. 2023;12(23)
[Google Scholar]

[4] Youm Y.S., Cho S.D., Lee S.H., Cho H.Y., . Total knee arthroplasty using a posterior cruciate ligament sacrificing medial pivot knee: minimum 5-year Follow-up results. Knee Surg Relat Res. 2014;26(3):135-140.
[Google Scholar]

[5] Ueyama H., Kanemoto N., Minoda Y., Yamamoto N., Taniguchi Y., Nakamura H., . Comparison of postoperative knee flexion and patient satisfaction between newly and conventionally designed medial pivot total knee arthroplasty: a 5-year follow-up matched cohort study. Arch Orthop Trauma Surg. 2022;142(8):2057-2064.
[Google Scholar]

[6] Karachalios T., Varitimidis S., Bargiotas K., Hantes M., Roidis N., Malizos K.N., . An 11- to 15-year clinical outcome study of the Advance Medial Pivot total knee arthroplasty: pivot knee arthroplasty. Bone Joint Lett J. 2016;98-B(8):1050-1055.
[Google Scholar]

[7] Macheras G.A., Galanakos S.P., Lepetsos P., Anastasopoulos P.P., Papadakis S.A., . A long term clinical outcome of the Medial Pivot Knee Arthroplasty System. Knee. 2017;24(2):447-453.
[Google Scholar]

[8] Bordini B., Ancarani C., Fitch D.A., . Long-term survivorship of a medial-pivot total knee system compared with other cemented designs in an arthroplasty registry. J Orthop Surg Res. 2016;11:44.
[Google Scholar]

[9] Bae D.K., Song S.J., Cho S.D., . Clinical outcome of total knee arthroplasty with medial pivot prosthesis a comparative study between the cruciate retaining and sacrificing. J Arthroplast. 2011;26(5):693-698.
[Google Scholar]

[10] Schutz P., Taylor W.R., Postolka B., et al . Kinematic evaluation of the GMK sphere implant during gait activities: a dynamic videofluoroscopy Study. J Orthop Res. 2019;37(11):2337-2347.
[Google Scholar]

[11] Scott G., Imam M.A., Eifert A., et al . Can a total knee arthroplasty be both rotationally unconstrained and anteroposteriorly stabilised? A pulsed fluoroscopic investigation. Bone Joint Res. 2016;5(3):80-86.
[Google Scholar]

[12] Bauer L., Woiczinski M., Thorwachter C., et al . Influence of kinematic alignment on femorotibial kinematics in medial stabilized TKA design compared to mechanical alignment. Arch Orthop Trauma Surg. 2023;143(7):4339-4347.
[Google Scholar]

[13] Karahan M., Acar E., Serarslan U., Gultekin A., . Medial pivot total knee arthroplasty: Mid-term results. Acta Orthop Belg. 2023;89(1):97-102.
[Google Scholar]

[14] Katchky A.M., Jones C.W., Walter W.L., Shimmin A.J., . Medial ball and socket total knee arthroplasty: five-year clinical results. Bone Joint Lett J. 2019;101-B(1_Supple_A):59-65.
[Google Scholar]

[15] Ohrn F.D., Gothesen O., Lastad Lygre S.H., et al . Decreased survival of medial pivot designs compared with cruciate-retaining designs in TKA without patellar resurfacing. Clin Orthop Relat Res. 2020;478(6):1207-1218.
[Google Scholar]

[16] Razick D., Akhtar M., Howell S.M., Nedopil A.J., Hull M.L., . The location of the centre of the proximal quadriceps tendon in kinematically aligned total knee arthroplasty is not associated with poor outcome scores or symptomatic patellar instability. J Exp Orthop. 2024;11(4)
[Google Scholar]

[17] Migliorini F., Maffulli N., Pilone M., et al . Mechanical versus kinematic alignment for total knee arthroplasty: a meta-analysis. Arch Orthop Trauma Surg. 2025;145(1):212.
[Google Scholar]

[18] Migliorini F., Pilone M., Schafer L., Simeone F., Bell A., Maffulli N., . Functional alignment in robotic-assisted total knee arthroplasty: a systematic review. Arch Orthop Trauma Surg. 2024;144(4):1741-1749.
[Google Scholar]

[19] Howick J.C.I., Glasziou P., Greenhalgh T., et al . The 2011 Oxford CEBM Levels of Evidence. 2011
[Google Scholar]

[20] Page M.J., McKenzie J.E., Bossuyt P.M., et al . The PRISMA 2020 statement: an updated guideline for reporting systematic reviews. Br Med J. 2021;372
[Google Scholar]

[21] 2022
[Google Scholar]

[22] Sterne J.A.C., Savovic J., Page M.J., et al . RoB 2: a revised tool for assessing risk of bias in randomised trials. Br Med J. 2019;366
[Google Scholar]

[23] Higgins J.P.T.S.J., Page M.J., Elbers R.G., Sterne J.A.C., . Chapter 8: assessing risk of bias in a randomized trial. 2022
[Google Scholar]

[24] Sterne J.A., Hernan M.A., Reeves B.C., et al . ROBINS-I: a tool for assessing risk of bias in non-randomised studies of interventions. Br Med J. 2016;355
[Google Scholar]

[25] McGuinness L.A., Higgins J.P.T., . Risk-of-bias VISualization (robvis): an R package and shiny web app for visualizing risk-of-bias assessments. Research Synthesis Methods n/a (n/a) 2020
[Google Scholar]

[26] Higgins J.P.T.T.J., Chandler J., Cumpston M., Li T., Page M.J., Welch V.A., . Cochrane Handbook for Systematic Reviews of Interventions Version 6.2. 2021
[Google Scholar]

[27] Batra S., Malhotra R., . Medial ball and socket total knee arthroplasty in Indian population: 5-Year clinical results. Clin Orthop Surg. 2022;14(1):90-95.
[Google Scholar]

[28] Chinzei N., Ishida K., Tsumura N., et al . Satisfactory results at 8 years mean follow-up after ADVANCE(R) medial-pivot total knee arthroplasty. Knee. 2014;21(2):387-390.
[Google Scholar]

[29] Choi N.Y., Y , Bae J.H., Do J.H., Chung S.J., Koh I.J., . Are midterm patient-reported outcome measures between rotating-platform mobile-bearing prosthesis and medial-pivot prosthesis different? A minimum of 5-Year Follow-Up Study. J Arthroplast. 2017;32(3):824-829.
[Google Scholar]

[30] Delman C.M., Ridenour D., Howell S.M., Hull M.L., . The posterolateral upslope of a low-conforming insert blocks the medial pivot during a deep knee bend in TKA: a comparative analysis of two implants with different insert conformities. Knee Surg Sports Traumatol Arthrosc. 2023;31(9):3627-3636.
[Google Scholar]

[31] Elorza S.P., O'Donnell E., Nedopil A., Howell S.M., Hull M.L., . Ball-in-socket medial conformity with posterior cruciate ligament retention neither limits internal tibial rotation and knee flexion nor lowers clinical outcome scores after unrestricted kinematically aligned total knee arthroplasty. Int Orthop. 2023;47(7):1737-1746.
[Google Scholar]

[32] Pacheco Elorza S., O'Donnell E., Delman C., Howell S.M., Hull M.L., . Posterior cruciate ligament retention with medial ball-in-socket conformity promotes internal tibial rotation and knee flexion while providing high clinical outcome scores. Knee. 2023;43:153-162.
[Google Scholar]

[33] Ettinger M., Tuecking L.R., Savov P., Windhagen H., . Higher satisfaction and function scores in restricted kinematic alignment versus mechanical alignment with medial pivot design total knee arthroplasty: a prospective randomised controlled trial. Knee Surg Sports Traumatol Arthrosc. 2024;32(5):1275-1286.
[Google Scholar]

[34] Howell S.M., Zabiba A., Nedopil A.J., Hull M.L., . The Forgotten Joint Score after total knee arthroplasty with a kinematic alignment-optimized femoral component matches total hip arthroplasty. Knee Surg Sports Traumatol Arthrosc 2025
[Google Scholar]

[35] Hu M., Xiang S., Xu H., Wang Y., Lv C., Zhang H., . Equivalence of clinical and radiological outcomes in cruciate-retaining and cruciate-substituting total knee arthroplasty with medial pivot knee: a comparative study. Heliyon. 2023;9(12)
[Google Scholar]

[36] Ishida K., Matsumoto T., Tsumura N., et al . No difference between double-high insert and medial-pivot insert in TKA. Knee Surg Sports Traumatol Arthrosc. 2014;22(3):576-580.
[Google Scholar]

[37] Jeremic D.V., Massouh W.M., Sivaloganathan S., Rosali A.R., Haaker R.G., Riviere C., . Short-term follow-up of kinematically vs. mechanically aligned total knee arthroplasty with medial pivot components: a case-control study. Orthop Traumatol Surg Res. 2020;106(5):921-927.
[Google Scholar]

[38] Kage T., Kono K., Tomita T., et al . Medial pivot total knee arthroplasty for valgus knees provides equivalent medial stability compared to that for varus knees: in vivo kinematic study. J Exp Orthop. 2024;11(4)
[Google Scholar]

[39] Karachalios T., Komnos G., Hantes M., Varitimidis S., . Evaluating the "Patella-Friendly" concept in total knee arthroplasty: a minimum 15-Year Follow-Up outcome Study comparing constant radius, Multiradius Cruciate-Retaining, and nonanatomical cruciate-retaining implants. J Arthroplast. 2021;36(8):2771-2778.
[Google Scholar]

[40] Koutp A., Schroedter R., Leitner L., Vielgut I., Leithner A., Sadoghi P., . Unrestricted kinematic alignment offers limited functional benefit over mechanical alignment in medial pivot total knee arthroplasty: a randomized controlled trial using conventional instrumentation. Knee Surg Sports Traumatol Arthrosc 2025
[Google Scholar]

[41] Niesen A.E., Tirumalai P.A., Howell S.M., Hull M.L., . A new tibial insert design with ball-in-socket medial conformity and posterior cruciate ligament retention has low tibial baseplate migration after unrestricted kinematically aligned total knee arthroplasty: a cohort study using radiostereometric analysis. Acta Orthop. 2024;95:758-764.
[Google Scholar]

[42] Obada B., Iliescu M.G., Costea D.O., Petcu L., Popescu A.I., . Comparative study of outcomes with total knee arthroplasty: medial pivot prosthesis vs posterior stabilized implant. Prospective randomized control. Int Orthop. 2025;49(3):629-639.
[Google Scholar]

[43] Risitano S., Sabatini L., Barberis L., Fusini F., Malavolta M., Indelli P.F., . Combining kinematic alignment and medial stabilized design in total knee arthroplasty: basic rationale and preliminary clinical evidences. J Orthop. 2020;21:427-431.
[Google Scholar]

[44] Ueyama H., Nakagawa S., Kishimura Y., et al . Long-term clinical results of alumina ceramic medial pivot total knee arthroplasty: a 10-year follow-up study. Arthroplasty. 2023;5(1):27.
[Google Scholar]

[45] Ueyama H., Kanemoto N., Minoda Y., Yamamoto N., Taniguchi Y., Nakamura H., . No difference in postoperative knee flexion and patient joint awareness between cruciate-substituting and cruciate-retaining medial pivot total knee prostheses: a 10-Year Follow-Up Study. J Arthroplast. 2022;37(2):279-285.
[Google Scholar]

[46] Vecchini E., Christodoulidis A., Magnan B., Ricci M., Regis D., Bartolozzi P., . Clinical and radiologic outcomes of total knee arthroplasty using the advance Medial Pivot prosthesis. A mean 7 years follow-up. Knee. 2012;19(6):851-855.
[Google Scholar]

[47] Xiang S., Wang Y., Lv C., Wang C., Zhang H., . Mid-term clinical outcomes and survivorship of medial-pivot total knee arthroplasty-a mean five year follow-up based on one thousand, one hundred and twenty eight cases. Int Orthop. 2021;45(11):2877-2883.
[Google Scholar]

[48] Clement N.D., MacDonald D., Simpson A.H., . The minimal clinically important difference in the Oxford knee score and Short Form 12 score after total knee arthroplasty. Knee Surg Sports Traumatol Arthrosc. 2014;22(8):1933-1939.
[Google Scholar]

[49] Brendle S.A., Krueger S., Grifka J., et al . Constraint of different knee implant designs under anterior-posterior shear forces and internal-external rotation moments in human cadaveric knees. Bioengineering (Basel). 2025;12(1)
[Google Scholar]

[50] Hamilton L.D., Shelburne K.B., Rullkoetter P.J., Barnes C.L., Mannen E.M., . Kinematic performance of medial pivot total knee arthroplasty. J Arthroplast. 2024;39(6):1595-1601 e1597.
[Google Scholar]

[51] Hodgeson S.M., Soeno T., Mears S.C., Stambough J.B., Barnes C.L., Stronach B.M., . The medial pivot design in total knee arthroplasty. Orthop Clin North Am. 2024;55(1):49-59.
[Google Scholar]

[52] Freeman M.A., Pinskerova V., . The movement of the knee studied by magnetic resonance imaging. Clin Orthop Relat Res. 2003;410:35-43.
[Google Scholar]

[53] Christen B., Kopjar B., . Second-generation bi-cruciate stabilized total knee system has a lower reoperation and revision rate than its predecessor. Arch Orthop Trauma Surg. 2018;138(11):1591-1599.
[Google Scholar]

[54] La Verde M., Belvedere C., Cammisa E., et al . Mechanically aligned second-generation medial pivot primary total knee arthroplasty does not reproduce normal knee biomechanics: a gait analysis Study. J Clin Med. 2024;13(18)
[Google Scholar]

[55] Dabirrahmani D., Farshidfar S., Cadman J., et al . Biomechanical improvements in gait following medial pivot knee implant surgery. Clin Biomech. 2024;116
[Google Scholar]

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Impact of implant generation on the outcomes in medial pivot total knee arthroplasty: a systematic review

Abstract