Trend of using cementless total knee arthroplasty: a nationwide analysis from 2015 to 2021.

BACKGROUND: Modern cementless total knee arthroplasty (TKA) fixation has shown comparable long-term outcomes to cemented TKA, but the trend of using cementless TKA remains unclear. This study aimed to investigate the trend of using cementless TKA based on a national database. METHODS: The patients undergoing cementless TKA between 2015 and 2021 were retrospectively extracted from the PearlDiver (Mariner dataset) Database. The annual percentage of cementless TKA was calculated using the following formula: annual number of cementless TKA/annual number of TKA. The trend of the number of patients undergoing cementless TKA was created according to a compounded annual growth rate (CAGR) calculation of annual percentages. Patient age, comorbidity, region, insurance type, etc., were also investigated. Differences were considered statistically significant at P < 0.05. RESULTS: Of the 574,848 patients who received TKA, 546,731 (95%) underwent cemented fixation and 28,117 (5%) underwent cementless fixation. From 2015 to 2021, the use of cementless TKA significantly increased by 242% from 3 to 9% (compounded annual growth rate (CAGR): + 20%; P < 0.05). From 2015 to 2021, we observed a CAGR greater than 15% for all age groups (< 50, 50-59, 60-69, 70-74, 75 +), insurance types (cash, commercial, government, Medicare, Medicaid), regions (Midwest, Northeast, South, West), sex (male and female), and certain comorbidities (osteoporosis, diabetes mellitus, tobacco use, underweight (BMI < 18.5), rheumatoid arthritis) (P < 0.05 for all). Patients undergoing TKA with chronic kidney disease, prior fragility fractures, and dementia demonstrated a CAGR of + 9%-13% from 2015 to 2021 (P < 0.05). CONCLUSION: From 2015 to 2021, the use of cementless TKA saw a dramatic increase in all patient populations. However, there is still no consensus on when to cement and in whom. Clinical practice guidelines are needed to ensure safe and effective use of cementless fixation.

Mode of Fixation and Survivorship in Primary Total Knee Arthroplasty in the American Joint Replacement Registry.

BACKGROUND: A recent rapid increase in cementless total knee arthroplasty (TKA) has been noted in the American Joint Replacement Registry (AJRR). The purpose of our study was to compare TKA survivorship based on the mode of fixation reported to the AJRR in the Medicare population. METHODS: Primary TKAs from Medicare patients submitted to AJRR from 2012 to 2022 were analyzed. The Medicare and AJRR databases were merged. Cox regression stratified by sex compared revision outcomes (all-cause, infection, mechanical loosening, and fracture) for cemented, cementless, and hybrid fixation, controlling for age and the Charlson comorbidity index (CCI). RESULTS: A total of 634,470 primary TKAs were analyzed. Cementless TKAs were younger (71.8 versus 73.1 years, P < .001) than cemented TKAs and more frequently utilized in men (8.2 versus 5.8% women, P < .001). Regional differences were noted, with cementless fixation more common in the Northeast (10.5%) and South (9.2%) compared to the West (4.4%) and Midwest (4.3%) (P < .001). No significant differences were identified in all-cause revision rates in men or women ≥ 65 for cemented, cementless, or hybrid TKA after adjusting for age and CCI. Significantly lower revision for fracture was identified for cemented compared to cementless and hybrid fixation in women ≥ 65 after adjusting for age and CCI (P = .0169). CONCLUSIONS: No survivorship advantage for all-cause revision was noted based on the mode of fixation in men or women ≥ 65 after adjusting for age and CCI. A significantly lower revision rate for fractures was noted in women ≥ 65 utilizing cemented fixation. Cementless fixation in primary TKA should be used with caution in elderly women.

[Successful medial unicompartmental knee arthroplasty-What are the most important surgical tricks?] / Erfolgsfaktoren für den medialen Teilgelenkersatz ­ Was sind die wichtigsten chirurgischen Tricks?

BACKGROUND: Unicompartmental knee arthroplasty (UKA) is an established surgical treatment option for end-stage anteromedial osteoarthritis with excellent functional outcomes and implant survival. Routine preoperative varus and valgus stress views are crucial for the selection of patients for unicompartmental or total knee arthroplasty. THERAPY: UKA is a soft-tissue based operation that aims to reconstruct the individual joint line and pre-arthritic alignment by restoring the physiological tension of the medial collateral and the cruciate ligaments. RESULTS: Current data for medial UKA show excellent results for both mobile and fixed bearing implant designs with the correct indication and surgical technique. Cementless fixation offers potential advantages over cemented implants. Registry data demonstrate that institutions and surgeons specializing in partial knee replacement (> 30 cases/year per surgeon, > 100/year per institution) with a high percentage of UKA relative to the total number of knee implants (> 20%) have significantly lower revision rates.

Is Tibial Bone Mineral Density Related to Sex, Age, Preoperative Alignment, or Fixation Method in Primary Total Knee Arthroplasty?

BACKGROUND: Cementless total knee arthroplasty (TKA) has regained interest for its potential for long-term biologic fixation. The density of the bone is related to its ability to resist static and cyclic loading and can affect long-term implant fixation; however, little is known about the density distribution of periarticular bone in TKA patients. Thus, we sought to characterize the bone mineral density (BMD) of the proximal tibia in TKA patients. METHODS: We included 42 women and 50 men (mean age 63 years, range: 50 to 87; mean body mass index 31.6, range: 20.5 to 49.1) who underwent robotic-assisted TKA and had preoperative computed tomography scans with a BMD calibration phantom. Using the robotic surgical plan, we computed the BMD distribution at 1 mm-spaced cross-sections parallel to the tibial cut from 2 mm above the cut to 10 mm below. The BMD was analyzed with respect to patient sex, age, preoperative alignment, and type of fixation. RESULTS: The BMD decreased from proximal to distal. The greatest changes occurred within ± 2 mm of the tibial cut. Age did not affect BMD for men; however, women between 60 and 70 years had higher BMD than women ≥ 70 years for the total cut (P = .03) and the medial half of the cut (P = .03). Cemented implants were used in 1 86-year-old man and 18 women (seven < 60 years, seven 60 to 70 years, and four ≥ 70 year old). We found only BMD differences between cemented or cementless fixation for women < 60 years. CONCLUSIONS: To our knowledge, this is the first study to characterize the preoperative BMD distribution in TKA patients relative to the intraoperative tibial cut. Our results indicate that while sex and age may be useful surrogates of BMD, the clinically relevant thresholds for cementless knees remain unclear, offering an area for future studies.

Cemented Versus Cementless Femoral Fixation for Total Hip Arthroplasty Following Femoral Neck Fracture in Patients Aged 65 and Older.

BACKGROUND: Femoral neck fractures are common in individuals over 65, necessitating quick mobilization for the best outcomes. There's ongoing debate about the optimal femoral component fixation method in total hip arthroplasty (THA) for these fractures. Recent U.S. data shows a preference for cementless techniques in over 93% of primary THAs. Nonetheless, cemented fixation might offer advantages like fewer revisions, reduced periprosthetic fractures, lesser thigh pain, and enhanced long-term implant survival for those above 65. This study compares cementless and cemented fixation methods in THA, focusing on postoperative complications in patients aged 65 and older. METHODS: We analyzed a national database to identify patients aged 65+ who underwent primary THA for femoral neck fractures between 2016 and 2021, using either cementless (n = 2,842) or cemented (n = 1,124) techniques. A 1:1 propensity-matched analysis was conducted to balance variables such as age, sex, and comorbidities, resulting in two equally sized groups (n = 1,124 each). We evaluated outcomes like infection, venous thromboembolism (VTE), wound issues, dislocation, periprosthetic fracture, etc., at 90 days, 1 year, and 2 years post-surgery. A P-value < 05 indicated statistical significance. RESULTS: The cemented group initially consisted of older individuals, more females, and higher comorbidity rates. Both groups had similar infection and wound complication rates, and aseptic loosening. The cemented group, however, had lower periprosthetic fracture rates (2.5 versus 4.4%, P = .02) and higher VTE rates (2.9 versus 1.2%, P = .01) at 90 days. After 1 and 2 years, the cementless group experienced more aseptic revision surgeries. CONCLUSIONS: This study, using a large, national database and propensity-matched cohorts, indicates that cemented femoral component fixation in THA leads to fewer periprosthetic fractures and aseptic revisions, but a higher VTE risk. Fixation type choice should consider various factors, including age, sex, comorbidities, bone quality, and surgical expertise. This data can inform surgeons in their decision-making process.

A multimodal assessment of cementless tibial baseplate fixation using radiography, radiostereometric analysis, and magnetic resonance imaging.

Fixation in cementless total knee arthroplasty is provided by osseous integration. Radiography, radiostereometric analysis (RSA), and magnetic resonance imaging (MRI) were used simultaneously to investigate fixation. Relationships between RSA-measured implant micromotions and MRI-evaluated osseous integration at the component-bone interface were assessed in 10 patients up to 6 months postoperation. Supine MRI (using multispectral imaging sequences) and RSA exams were performed to evaluate osseous integration and measure longitudinal migration, respectively. Inducible displacement was measured from standing RSA exams. Radiolucent lines were detected on conventional radiographs. Of 10 patients, 6 had fibrous membranes detected on MRI. No fluid or osteolytic interfaces were found, and no components were scored loose. Of 10 patients, 6 had radiolucent lines detected. Average maximum total point motion (MTPM) for longitudinal migration at 6 months was 0.816 mm (range 0.344-1.462 mm). Average MTPM for inducible displacement at 6 months was 1.083 mm (range 0.553-1.780 mm). Fictive points located in fibrous-classified baseplate quadrants had greater longitudinal migration than fictive points located in baseplate quadrants with normal interfaces at 2 weeks (p = 0.031), 6 weeks (p = 0.046), and 3 months (p = 0.047), and greater inducible displacements at 3 months (p = 0.011) and 6 months (p = 0.045). Greater early micromotion may be associated with the presence of fibrous membranes at the component-bone interface. Clinical significance: This multimodal imaging study contributes knowledge of the fixation of modern cementless TKA, supporting the notion that osseous integration is important for optimal implant fixation.

An Anterior Spike Decreases Bone-Implant Micromotion in Cementless Tibial Baseplates for Total Knee Arthroplasty: A Biomechanical Study.

BACKGROUND: Cementless tibial baseplates in total knee arthroplasty include fixation features (eg, pegs, spikes, and keels) to ensure sufficient primary bone-implant stability. While the design of these features plays a fundamental role in biologic fixation, the effectiveness of anterior spikes in reducing bone-implant micromotion remains unclear. Therefore, we asked: Can an anterior spike reduce the bone-implant micromotion of cementless tibial implants? METHODS: We performed computational finite element analyses on 13 tibiae using the computed tomography scans of patients scheduled for primary total knee arthroplasty. The tibiae were virtually implanted with a cementless tibial baseplate with 2 designs of fixation of the baseplate: 2 pegs and 2 pegs with an anterior spike. We compared the bone-implant micromotion under the most demanding loads from stair ascent between both designs. RESULTS: Both fixation designs had peak micromotion at the anterior-lateral edge of the baseplate. The design with 2 pegs and an anterior spike had up to 15% lower peak micromotion and up to 14% more baseplate area with micromotions below the most conservative threshold for ingrowth, 20 µm, than the design with only 2 pegs. The greatest benefit of adding an anterior spike occurred for subjects who had the smallest area of tibial bone below the 20 µm threshold (ie, most at risk for failure to achieve bone ingrowth). CONCLUSIONS: An anteriorly placed spike for cementless tibial baseplates with 2 pegs can help decrease the bone-implant micromotion during stair ascent, especially for subjects with increased bone-implant micromotion and risk for bone ingrowth failure.

The effect of activity on the outcome of cementless mobile bearing unicompartmental knee replacements.

BACKGROUND: Many surgeons consider high activity levels a contraindication to Unicompartmental Knee Replacement (UKR). Cementless fixation is of particular concern given the lack of cement to augment primary stability. We assessed the effect of pre and post-operative activity levels on the outcomes of cementless UKRs. METHODS: A prospective cohort of 1000 medial cementless mobile bearing UKR were analysed. Patients were categorised by their pre-operative and highest post-operative Tegner Activity Score (TAS) and results compared between groups. Outcomes of interest included implant survival, Oxford Knee Score (OKS) and the American Knee Society Score - Objective/Functional (AKSS-O/F). RESULTS: Increasing post-operative activity were not associated with higher revision rates. The 10-year survival of the high activity group (TAS ≥ 5, 96.7% (CI 91.3-98.8), and low/medium activity group (TAS ≤ 4, 98.1% (CI 96.5-99.0)) were not significantly different (p = 0.57). The mean 10-year OKS of the high activity group (46.5, SD 3.1) was significantly (p < 0.001) higher than that of the low/medium activity group (41.3, SD 7.7). There was a significant trend for increasing activity being associated with increasing AKSS-F at 5-years (p < 0.001) and 10 years (p = 0.01) and increasing AKSS-O at 5 years (p < 0.001). Higher pre-operative activity did not significantly increase revision rates and resulted in significantly higher 5-year post-operative scores. CONCLUSIONS: Neither higher pre-operative nor post-operative activity were associated with increased revision rates, but both were associated with better post-operative function. Therefore activity should not be considered a contraindication to cementless mobile bearing UKR and not be restricted post-operatively.

Axial and Sagittal Rotation of Cementless Tibial Baseplates Occurs in Bone Under Joint Loading.

BACKGROUND: There has been a recent increase in the use of cementless fixation for primary total knee arthroplasty. While the early results of contemporary cementless implants are promising, understanding the behavior of cementless tibial baseplates under loading remains an ongoing interest. The objective of this study was to identify the pattern of displacement that occurred under loading for a single cementless tibial baseplate design at one year post operation for stable and continuously migrating implants. METHODS: There were 28 subjects from a previous trial of a pegged highly porous cementless tibial baseplate evaluated. Subjects underwent supine radiostereometric exams from two weeks through one year after surgery. At one year, subjects also underwent a standing radiostereometric exam. Fictive points on the tibial baseplate model were used to relate translations to anatomical locations. Migration over time was calculated to determine if subjects displayed stable or continuous migration. The magnitude of inducible displacement between the supine and standing exams was calculated. RESULTS: Inducible displacement patterns were similar between stable and continuously migrating tibial baseplates. Displacements were greatest in the anterior-posterior axis followed by the lateral-medial axis. Correlation of displacements between adjacent fictive points in these axes indicated an axial rotation of the baseplate occurred under loading (r2 = 0.689-0.977, P < .001). Less displacement occurred in the superior-inferior axis and correlations indicated an anterior-posterior tilt of the baseplate occurred under loading (r2 = 0.178-0.226, P = .009-.023). DISCUSSION: From supine to standing position the predominant pattern of displacement for this cementless tibial baseplate was axial rotation, with some subjects also displaying an anterior-posterior tilt.

The effect of body mass index on the outcomes of cementless medial mobile-bearing unicompartmental knee replacements.

PURPOSE: Given an increasingly overweight population, unicompartmental knee replacements (UKRs) are being performed in patients with higher body mass indices (BMIs). There are concerns that cemented fixation will not last. Cementless fixation may offer a solution, but the long term results in different BMI groups has not been assessed. We studied the effect of BMI on the outcomes of cementless UKRs. METHODS: A prospective cohort of 1000 medial cementless mobile-bearing UKR with a mean follow up of 6.6 years (SD 2.7) were analysed. UKRs were categorised into four BMI groups: (1) ≥ 18.5 to < 25 kg/m2 (normal), (2) 25 to < 30 kg/m2 (overweight), (3) 30 to < 35 kg/m2 (obese class 1) and (4) ≥ 35 kg/m2 (obese class 2). Implant survival was assessed using endpoints reoperation and revision. Functional outcomes were assessed. RESULTS: Ten-year cumulative revision rate for the normal (n = 186), overweight (n = 434), obese class 1 (n = 213) and obese class 2 (n = 127) groups were 1.8% (CI 0.4-7.4), 2.6% (CI 1.3-5.1), 3.8% (CI 1.5-9.2) and 1.7% (CI 0.4-6.8) with no significant differences between groups (p = 0.79). The 10-year cumulative reoperation rates were 2.7% (CI 0.8-8.2), 3.8% (CI 2.2-6.6), 5.2% (CI 2.5-10.7) and 1.7% (CI 0.4-6.8) with no significant differences between groups (p = 0.44). The 10-year median Oxford Knee Score were 43.0, 46.0, 44.0 and 38.0 respectively. CONCLUSION: Cementless mobile-bearing UKR has low 10-year reoperation and revision rates across in all BMI groups, and there are no significant differences between the groups. Although higher BMI groups had slightly worse functional outcomes, the improvement in function compared to preoperatively  tended to be better. This study suggests that BMI should not be considered a contraindication for the cementless mobile-bearing UKR.

Clinical results and radiological bony adaptations on a cementless short-stem prosthesis - A comparative study between anatomical and reverse total shoulder arthroplasty.

INTRODUCTION: Although the use of short stem and stemless shoulder prosthesis is trending, the surgical outcome may vary due to varying biomechanics. Objectives were to evaluate and compare the short-term clinical results and radiological changes between anatomical total shoulder arthroplasty (TSA) and reverse TSA (rTSA) with a short-stem humeral design. HYPOTHESIS: There is no clinical and radiological difference between TSA and rTSA using a short-stem humeral design. METHODS: This retrospective study included 66 patients who underwent TSA and rTSA (33 patients each) with a minimum 2-year follow-up. Radiographic findings, including preoperative Tingart cortical index (TCI), postoperative filling ratios of metaphysis (FRmet) and diaphysis (FRdia), bone adaptations, and osteolysis around the humeral stem at the immediate postoperative period, and the most recent follow-up were measured. Pre and postoperative Constant-Murley score, subjective shoulder value (SSV), and complications were noted. RESULTS: At a mean follow-up of 27 (range 24-50) months, FRmet was significantly higher in rTSA group than the TSA group (0.65 vs. 0.60, p=0.009). Bone resorption was similar in both groups (p=0.76) and was correlated to a lower TCI value of<2.9mm (p=0.02). Despite significant clinical improvement in individual groups, the comparison between groups was non-significant (p>0.05). Negative correlation was observed between TCI and total clinical score (p=0.045) in TSA group, active external rotation (p=0.019), activity (p=0.005), SSV (p=0.008) and total score (p=0.025) in rTSA group. Radiographic changes were not influenced by patient characteristics and clinical results (p>0.05). CONCLUSION: Although no radiographic difference was observed between TSA and rTSA, better short-term clinical results observed with the usage of the short-stem humeral design prosthesis are encouraging. LEVEL OF EVIDENCE: III; Retrospective cohort study.

Predicting friction at the bone - Implant interface in cementless total knee arthroplasty.

Cementless total knee arthroplasty (TKA) components have rough and porous surface coatings which can enhance bone ingrowth and stability at the bone-implant. To achieve primary stability in the postoperative period where no apposition is formed, the resistance against motions between bone and implant is optimized by increasing the friction at the interface. This is necessary, as excessive relative motions can inhibit bone ingrowth, which might result in loosening and pain. In this research, it was found that the friction can be predicted by measuring the surface morphology of rough implants, and calculating the corresponding perpendicular and lateral contact area parameters. The ratio between these areas, is used to predict the resulting coefficient of friction (COF). This is validated experimentally, by analysing the tribological behaviour of 2 porous and rough titanium coatings against human cadaveric knee bones using reciprocal friction tests with varying normal loads. The results for 2 different coatings showed similar findings for the predicted COF (0.75 and 0.88) versus the calculated values based on the measurement (0.82 and 0.86) proving the feasibility of the approach.

Should patient age thresholds dictate fixation strategy in total hip arthroplasty?

AIMS: Total hip arthroplasty (THA) is a very successful and cost-effective operation, yet debate continues about the optimum fixation philosophy in different age groups. The concept of the 'cementless paradox' and the UK 'Getting it Right First Time' initiative encourage increased use of cemented fixation due to purported lower revision rates, especially in elderly patients, and decreased cost. METHODS: In a high-volume, tertiary referral centre, we identified 10,112 THAs from a prospectively collected database, including 1,699 cemented THAs, 5,782 hybrid THAs, and 2,631 cementless THAs. The endpoint was revision for any reason. Secondary analysis included examination of implant survivorship in patients aged over 70 years, over 75 years, and over 80 years at primary THA. RESULTS: Cemented fixation had the lowest implant survival in all age groups, with a total ten-year survivorship of 97.0% (95% confidence interval (CI) 95.8 to 97.8) in the cemented group, 97.6% (95% CI 96.9 to 98.1) in the hybrid group, and 97.9% (95% CI 96.9 to 98.6) in the cementless group. This was not statistically significant (p = 0.092). There was no age group where cemented fixation outperformed hybrid or cementless fixation. CONCLUSION: While all fixation techniques performed well at long-term follow-up, cemented fixation was associated with the lowest implant survival in all age groups, including in more elderly patients. We recommend that surgeons should carefully monitor their own outcomes and use fixation techniques that they are familiar with, and deliver the best outcomes in their own hands. Cite this article: Bone Joint J 2022;104-B(2):206-211.

Polka dot cementless talar component in enhancing total ankle replacement fixation: A parametric study using the finite element analysis approach.

The primary stability of a total ankle replacement (TAR) is essential in preventing long-term aseptic loosening failure and could be quantified based on micromotion at the bone-prosthesis interface subjected to physiological loading during the normal walking. A 3D finite element analysis was conducted to investigate the current commercial STAR™ Ankle TAR bone-prosthesis interface relative micromotion (BPIRM) with addition of the talus bone minimum principal bone stresses (MPBS). Comparison was made to the proposed polka dot designs with the hemispheric feature that was demonstrated to enhance BPIRM. Parametric studies were conducted on the hemispheric features with changes in its diameter, length and shape. The FE results indicated high BPIRM at the talar component was primarily contributed by de-bonding (in the normal direction) between the talus bone and talar component. The MPBS were found to be most significant in the superior anterior and superior medial regions of the talus bone. When the pin length was increased from 1.5 to 3 mm, the BPIRM was predicted to fall below 50 µm in favour of bone in-growth. Based on the practicality of the prosthesis implantation during the surgical procedure, the final design that incorporated both the initial polka dot and 3 mm pin length in a crisscross manner was deemed to be a favorable design with reduced BPIRM and MPBS hence lowering the risk of long-term aseptic loosening.

Preliminary outcomes of the cementless UNITED hip system for primary total hip arthroplasty at a minimum 2-year follow-up.

INTRODUCTION: This study aimed to report the initial results of the cementless UNITED hip system in primary total hip arthroplasty (THA) with a minimum follow-up of 2 years. METHODS: We retrospectively studied a consecutive series of 203 cementless THAs in 180 patients operated between 2015-2017. We included 89 female and 91 male patients with a mean age of 67 (28 to 89) years. The mean follow-up was 40 (29 to 62) months. Clinical outcome scores and radiographs were measured. Survival was calculated defining failure as the need for any further femoral or acetabular revision, irrespective of the reason. RESULTS: No femoral component loosening was detected. One patient had a Vancouver-B1 intraoperative periprosthetic femoral fracture treated with implant retention and cerclage wires. Two acetabular components were revised for aseptic loosening. Three patients suffered an acute infection treated with debridement, antibiotics, and implant retention. The mean Merle d'Aubigné et Postel scores improved from 13 (4 to 16) points preoperatively to 17 (12 to 18) points at the latest follow-up (p < 0.001). At a mean time of 40 months of follow-up, the survival was 99% and 100% for the acetabular and the femoral components, respectively. CONCLUSION: This cementless design showed excellent preliminary outcomes in terms of fixation and patient satisfaction, comparable to that of other well-known similar systems.

The effect of age on the outcomes of cementless mobile bearing unicompartmental knee replacements.

PURPOSE: Unicompartmental Knee Replacements (UKR) are being performed in patients with increasing demands and life expectancies with surgical concerns that cemented fixation will not last. Cementless fixation may offer a solution, but the results in different age groups have not been assessed. The effect of age at surgery on the outcomes of cementless UKRs was investigated. METHODS: A prospective cohort of 1000 medial cementless mobile bearing UKR were analysed. Patients were categorised into four age groups (< 55, 55 to < 65, 65 to < 75 and ≥ 75 years). Implant survival was assessed using endpoints reoperation, revision and major revision requiring revision knee replacement components. Functional outcomes were assessed. RESULTS: 10 year cumulative revision rate for the < 55, 55 to < 65, 65 to < 75 and ≥ 75 groups were 2.1% (CI 0.6-6.1), 1.8% (CI 0.6-5.3), 3.2% (CI 1.5-6.5) and 4.1% (1.7-9.6) with no differences between groups (p = 0.52). Two of the 22 revisions were considered major. The 10 year cumulative reoperation rates were 4.5% (CI 2.0-10.0), 3.0% (CI 1.3-6.5), 3.8% (CI 2.0-7.1) and 4.1% (CI 1.7-9.6) with no differences between groups (p = 0.81). The 10 year median Oxford Knee Scores were 42.5, 46.5, 45 and 42.5, respectively. The 10 year median Objective American Knee Society Scores were 95 for all age groups. CONCLUSION: The cementless mobile bearing UKR has low reoperation and revision rates and similar functional outcomes in all age groups. Cementless UKR should be used in all age groups and age should not be considered a contraindication. LEVEL OF EVIDENCE: III.

Femoral and tibial cementless fixation neither increases blood loss nor impedes early functional recovery: A randomized controlled trial.

Background: Whether cementless fixation on femoral and tibial components increases blood loss during total knee arthroplasty (TKA) is unclear. The purpose of this randomized controlled trial was to compare blood loss and early functional recovery between patients who underwent cementless or cemented TKA. Methods: Between November 2021 and April 2022, sixty-one eligible patients at our medical center were randomized to cementless and cemented group. The primary outcome was total blood loss (TBL). Secondary outcomes were drainage, knee swelling, anemia, transfusion, hematological indicators, early functional recovery, and postoperative complications. The early functional recovery included range of motion (ROM), Hospital for Special Surgery (HSS) score, walking distance. Results: A total of 61 patients were analyzed, of whom 30 underwent cementless fixation. On postoperative day 1, the mean TBL was 394.39 ml (SD 182.97 ml) in the cementless group and 382.41 ml (SD 208.67 ml) in the cemented group (P = 0.863). By postoperative day 3, the corresponding mean TBL was higher at 593.48 ml (SD 230.04 ml) and 603.80 ml (SD 213.16 ml) (P = 0.751). The two groups did not differ significantly in drainage, knee swelling, anemia, levels of hemoglobin or hematocrit or platelets, ROM, HSS score, walking distance, or rates of transfusion or postoperative complications. Conclusions: Cementless fixation on femoral and tibial components during TKA does not increase blood loss or impede early functional recovery, which suggests that clinicians need not worry about blood loss and early functional recovery when deciding what type of fixation to perform during TKA. Trial registration: Number: ChiCTR2100052857; Date: November 6, 2021.

Short- to Mid-Term Clinical Outcomes of Posterior-Stabilized Cementless Total Knee Arthroplasty with Trabecular Metal Components.

OBJECTIVE: This study aimed to evaluate the short- to mid-term clinical results of posterior-stabilized trabecular metal total knee arthroplasty (TKA) with cementless fixation of all components and investigate the radiographic changes of tibial and patellar components and cut bone surfaces over time. METHODS: We retrospectively collected the data of 128 knees from 88 consecutive patients who had undergone initial TKA with NexGen LPS-Flex TM implants. A total of 66 knees from 45 patients (mean ± standard deviation age: 70.3 ± 7.5 years) met the selection criteria, which had been employed cementless fixation of all parts and at least 3 years of postoperative follow-up duration. Clinical evaluations included range of motion, conventional knee score, function score, postoperative complications, and revision. For radiological evaluations, the bone contact surface of each implant was divided into 7 zones for tibial component and 2 zones for patellar component. Each region was examined immediately after surgery, at 6 and 12 months, and then every year afterwards. RESULTS: The mean observation period of 45 subjects was 4.2 years. Adequate fixation of tibial components was maintained during follow-up, although the patellar components of 2 knees required revision after repeated falls. No loosening was observed in any implants. The initial gap in tibial components disappeared in all knees, and a reactive line remained in 4 knees. There were no revisions, except for 2 cases, which were ascribed to patellar component fracture caused by repeated falls. CONCLUSION: Cementless posterior-stabilized trabecular metal TKA appears to be a good surgical option. Longer-term examination for revision cases is required to validate our results.

Effect of gap balancing and measured resection techniques on implant migration and contact kinematics of a cementless total knee arthroplasty.

BACKGROUND: The purpose of this study was to compare implant migration and tibiofemoral contact kinematics of a cementless primary total knee arthroplasty (TKA) implanted using either a gap balancing (GB) or measured resection (MR) surgical technique. METHODS: Thirty-nine patients underwent TKA via a GB (n = 19) or a MR (n = 20) surgical technique. Patients received an identical fixed-bearing, cruciate-retaining cementless implant. Patients underwent a baseline radiostereometric analysis (RSA) exam at two weeks post-operation, with follow-up visits at six weeks, three months, six months, and one year post-operation. Migration including maximum total point motion (MTPM) of the femoral and tibial components was calculated over time. At the one year visit patients also underwent a kinematic exam via RSA. RESULTS: Mean MTPM of the tibial component at one year post-operation was not different (mean difference = 0.09 mm, p = 0.980) between the GB group (0.85 ± 0.37 mm) and the MR group (0.94 ± 0.41 mm). Femoral component MTPM at one year post-operation was also not different (mean difference = 0.27 mm, p = 0.463) between the GB group (0.62 ± 0.34 mm) and the MR group (0.89 ± 0.44 mm). Both groups displayed similar kinematic patterns. CONCLUSIONS: There was no difference in implant migration and kinematics of a single-radius, cruciate retaining cementless TKA performed using a GB or MR surgical technique. The magnitude of migration suggests there is low risk of early loosening. The results provide support for using the cementless implant with either a GB or MR technique.

No effect in primary stability after increasing interference fit in cementless TKA tibial components.

Cementless total knee arthroplasty (TKA) implants rely on interference fit to achieve initial stability. However, the optimal interference fit is unknown. This study investigates the effect of using different interference fit on the initial stability of tibial TKA implants. Experiments were performed on human cadaveric tibias using a low interference fit of 350 µm of a clinically established cementless porous-coated tibial implant and a high interference fit of 700 µm. The Orthoload peak loads of gait and squat were applied to the specimens with a custom-made load applicator. Micromotions and gaps opening/closing were measured at the bone-implant interface using Digital Image Correlation (DIC) in 6 regions of interest (ROIs). Two multilevel linear mixed-effect models were created with micromotions and gaps as dependent variables. The results revealed no significant differences for micromotions between the two interference fits (gait p = 0.755, squat p = 0.232), nor for gaps opening/closing (gait p = 0.474, squat p = 0.269). In contrast, significant differences were found for the ROIs in the two dependent variables (p < 0.001), where more gap closing was seen in the posterior ROIs than in the anterior ROIs during both loading configurations. This study showed that increasing the interference fit from 350 to 700 µm did not influence initial stability.