Cementless Versus Cemented Total Knee Arthroplasty: Concise Midterm Results of a Prospective Randomized Controlled Trial

Adhesion of bone cement to porous and nonporous 3D printed surfaces

Bone cement is an adhesive commonly used to bond orthopedic implants to bone during a surgical procedure. Total joint replacements such as total knee, hip, shoulder, or ankle arthroplasties have metal or polymer components that are commonly cemented. However, implant failures can occur via debonding at the implant-cement interface, suggesting sub-optimal adhesion of the cement to the implant. In parallel, the orthopedic implant industry is seeing a significant rise in additive manufacturing (AM), which enables the seamless integration of surface porosity enhanced osseointegration in cementless procedures. However, there is a lack of foundational data or understanding of how bone cement adheres to 3D printed surfaces as a function of varying topography. This study evaluates adhesion of cement to clinically relevant printed implant surfaces, porous topographies, and materials. Adhesion strength of cemented samples was tested in shear. Surface porous layers were compared to traditional implant surface finishes (blasted, machined, polished). The impact of 3D printed surface porosity size and depth was also investigated. Testing revealed that the adhesive strength of porous surfaces (26.3 ± 3.1 MPa) was more than double the adhesive strength of all non-porous surfaces (the highest being the as-printed surface with a strength of 11.3 ± 2.5 MPa). The study also demonstrated porosity and layer-depth dependent performance trade-offs, with the best performing group having a 2x2x2 mm3 unit cell size and 0.50 mm layer depth and a shear strength of 26.31 ± 3.10 MPa. These results provide a foundation for improving designs of emerging 3D printed orthopedic implants that can be both cemented and cementless.

To Cement or Not? Ten-Year Results of a Prospective, Randomized Study Comparing Cemented Versus Cementless Total Knee Arthroplasty

BACKGROUND

The optimal mode of fixation for total knee arthroplasty (TKA) continues to be a subject of debate.

METHODS

There were 100 cases enrolled to compare cemented and cementless TKA using a modular trabecular metal tibia. This is a report on the 91 cases with follow-up information, including 67 cases with a minimum 10-year follow-up: 36 cases in the cemented cohort (A) and 31 cases in the cementless cohort (B). We previously reported the 2- and 5-year results for this prospective, randomized trial. Knee Society Scores (KSS) and Oxford scores (OKS) were collected pre- and postoperatively.

RESULTS

Mean KSS (94.4, 89.1, P = 0.21) and OKS (45.1, 43.5, P = 0.12) were similar in both groups. Group A had two revisions at 5-year follow-up, with three additional revisions for polyethylene wear, osteolysis, and loosening at 10-year follow-up. Group B had two revisions at 5-year follow-up, with two additional revisions for polyethylene wear and instability and instability due to laxity at 10-year follow-up. In total, two group A cases and one group B case were revised for implant fixation complications. Survivorship with any revision as an endpoint was equivalent between the two cohorts (91.5%, 95.9%, P = 0.60), as was survivorship using tibial tray revision as an endpoint (93.7%, 95.9%, P = 0.55). No cases demonstrated any progressive radiolucencies. Group A had five cases with osteolysis (80% tibial), and Group B had two cases of osteolysis (0% tibial).

CONCLUSION

Cementless and cemented TKA had equivalent patient-reported outcomes and survivorship at 10-year follow-up. Cemented fixation had a higher rate of osteolysis and loosening, which may be related to increased third-body wear. Cementless fixation shows immense potential as a successful option for many patients. Updates to this study cohort are planned at 15- and 20-year intervals to obtain long-term outcomes.

Long-Term Outcomes of Cementless Versus Hybrid Cemented Total Knee Arthroplasty: A Minimum 10-Year Follow-Up

Background: Although cemented total knee arthroplasty (TKA) is considered the standard fixation technique, the emerging trend toward cementless fixation has created the need for a detailed comparison. In a previous study, we reported the 5-year results comparing cementless and hybrid cemented TKAs using the same implant design. The purpose of this study was to assess the long-term follow-up at a minimum of 10 years. Methods: A retrospective analysis was performed on 120 TKAs (60 cementless, 60 hybrid cemented) conducted between 2003 and 2007 using the e.motion posterior cruciate-retaining knee prosthesis with a floating-platform mobile polyethylene bearing (Aesculap, Tuttlingen, Germany). Demographic and clinical data were collected; radiographic follow-up was performed with attention to signs of loosening, while complications and revision surgery were assessed using competing risk analysis. Operative time was recorded as an indicator of surgical efficiency. Results: At 10 years, 59 TKAs (54 patients) were available for long-term follow-up. Both fixation groups demonstrated significant improvement in Knee Society Scores (KSSs) compared to preoperative values (p < 0.001). However, there was no significant difference in KSSs between the two groups at 10 years follow-up (p = 0.480). The 10-year cumulative incidence of revision was 8.4% in both groups (p = 0.721), and that of aseptic loosening was identical at 3.4% (p = 0.967). Although radiolucent lines were noted in three tibial components of the cementless group, the difference was not statistically significant (p = 0.075). Notably, the cementless group demonstrated a significantly shorter operative time with a mean difference of 10 min (p = 0.017). Conclusions: At a minimum follow-up of 10 years, there were no significant differences between the hybrid cemented and cementless groups in revision rates, cumulative incidences, clinical scores, or radiological signs of loosening, confirming the long-term effectiveness of both fixation methods in clinical practice.

No difference in 5-year survivorship between cemented versus cementless total knee arthroplasty in a cohort of 5266 patients using a deep-dish mobile bearing implant

PURPOSE

The best fixation method for total knee arthroplasty (TKA) remains controversial. The aim of this study is to compare the effect of cemented and cementless fixation on prosthesis survivorship. Our primary hypothesis is that there is no difference in survivorship between cemented and cementless TKA. Our secondary hypothesis is that there is no difference in aseptic revisions and functional outcomes between cemented and cementless TKA at mid-term follow-up.

METHODS

A multicentre retrospective study was done using data collected prospectively in a large cohort. The same deep-dish mobile bearing design was used for both cemented and cementless TKA. Patients were divided into two groups according to the fixation method. The survival rate between cemented and cementless TKA was compared. Functional outcomes were collected preoperatively and at the 5-year follow-up.

RESULTS

Of the 5266 primary TKA included, 4549 were cementless, and 717 were cemented. At 5 years, there was no significant difference between the survivorship of the cementless (98.7% [95% confidence interval, CI: 98.2-99.1]) and cemented TKA (97.6%, [95% CI: 94.1-99.1]) (p = 0.468). There was no significant difference in the surgery-free survival at 5 years between cementless (95.8% [95% CI: 94.9-96.5]) and cemented TKA (95.5% [95% CI: 92.1-97.5]) (p = 0.508) as well as in aseptic revision: cementless (96.9% [95% CI: 96.2-97.5]) and cemented TKA (97.5 [95% CI: 95.5-98.6]) (p = 0.355). There was no significant difference in the functional outcomes at 5 years.

CONCLUSION

There was no observed difference in survivorship between cemented and cementless TKA at 5 years in this cohort of 5266 patients. Additionally, rates of reoperation and aseptic revision were similar across both fixation methods, and clinical outcomes did not differ significantly. Therefore, it may be suggested that cementless fixation is a safe option for primary TKA.

LEVEL OF EVIDENCE

Level III.

Tibial Components Placed in Constitutional Varus Alignment in Primary Total Knee Arthroplasty: A 5-Year Survivorship Analysis

BACKGROUND

Placing tibial components in varus alignment has been controversial due to concerns of loosening and subsequent revision. The purpose of this study was to compare 5-year survivorship of tibial components placed in 3° or greater of varus alignment versus neutral mechanical alignment (nMA).

METHODS

This was a retrospective matched cohort study of 530 patients with 265 patients who underwent primary robotic-assisted total knee arthroplasty (TKA) with tibial components intentionally placed in varus matched to a control group of 265 patients who underwent TKA using manual instrumentation with tibial components placed in nMA. Both cementless and cemented implants were used in both groups. There was no difference between groups with respect to patient sex or age. There were 100 and 87.5% of patients who had a minimum 5-year follow-up in the tibial varus and nMA groups, respectively. Outcomes included survivorship, complications, revisions, and patient-reported outcome measures.

RESULTS

All-cause survivorship at 5 years postoperatively was 98% in the group with constitutional tibial varus and 96% in the nMA group (P = 0.12). There were no cases of aseptic loosening in the group with tibial component varus. There were five patients who required revision in the varus group versus 14 in the nMA group (P = 0.02). There was a significant difference in nonrevision intervention for stiffness between the two groups in favor of the varus group (three versus 14, P = 0.003).

CONCLUSIONS

Similar survivorship was demonstrated at a mid-term 5-year follow-up between patients undergoing primary TKA using a functional alternative alignment concept with tibial components intentionally placed in 3° or greater of varus compared to nMA. Tibial components placed in constitutional or anatomic varus, in an attempt to restore the native oblique joint line along with well-balanced gaps, demonstrated 98% survivorship at 5 years.

Short-Term Outcomes of Noncemented Total Knee Arthroplasty in Patients With Morbid Obesity

INTRODUCTION

Noncemented primary total knee arthroplasty (TKA) compromises over 14% of all primary TKA procedures reported in the American Joint Replacement Registry. While studies have indicated similar outcomes for cemented and noncemented TKA in obese individuals, the efficacy and safety of noncemented TKA in morbidly obese patients (body mass index [BMI] ≥ 40 kg/m2) remain unexplored. This study compares short-term postoperative outcomes and complications between noncemented and cemented TKA in morbidly obese patients.

METHODS

A retrospective review of 605 cases of patients with a BMI of at least 40 kg/m2 (22.5% of 2,691 total cases at a single tertiary center) who underwent TKA was conducted. All patients had a minimum follow-up of 1 year. Data collected included age, BMI, sex, race, ethnicity, American Society of Anesthesiologists status, and the Charlson Comorbidity Index. Postoperative complications were tracked, including 90-day readmission, 1-year mortality, 1-year revision surgery, wound complications, fractures, and infections. Categorical variables were analyzed with chi-square tests and continuous variables with t-tests.

RESULTS

Of the included patients with a BMI ≥ 40 kg/m2, 40 (6.6%) received noncemented TKA. The noncemented TKA group had a lower mean BMI (43.3 ± 3.1 vs. 45.0 ± 4.4; P = 0.012) and a higher proportion of male patients compared with the cemented group (n = 17 [42.5%] vs. n = 143 [25.3%]; P = 0.028). Surgical time was shorter for noncemented TKA (97 ± 27 minutes) than for cemented TKA (118.0 ± 39.4 minutes; P = 0.001). No significant differences were found in length of stay and postoperative complications, including 90-day readmission, 1-year mortality, revision surgery rates, wound complications, fractures, and infections.

CONCLUSION

The findings of the study suggest that noncemented TKA may be a feasible, safe alternative and not inferior to the standard cemented TKA in patients with morbid obesity with the benefit of decreasing surgical time.

Early radiographic evaluation of an anatomic porous tantalum tibia: A prospective, multi-center, non-randomized clinical study

BACKGROUND

Excellent survival rates have been reported for total knee arthroplasty (TKA) performed with cementless porous metal tibial components. More data, however, is necessary to assess the survival and radiographic results of modular implants with anatomic designs. The purpose of this study was to investigate the early radiographic, survival, and clinical outcomes of a cementless tantalum metal tibial implant with a modular anatomic component.

METHODS

An early follow-up of a prospective, multi-center, non-randomized outcomes study of patients who received cementless tibial implants in primary TKA between 2018 and 2020 was performed. A total of 148 implants were available for review. Radiographs, the Forgotten Joint Score (FJS-12), Oxford Knee Score (OKS), patient satisfaction, and adverse events were collected for at least two-years post-operative. A minimum of two-years follow-up was available for 119 patients and evaluated for progressive radiolucent lines (RLLs).

RESULTS

The mean follow-up was 2.2 ± 0.6 years, and the two-year implant survival rate was 98.59% (95% C.I.: 94.46, 99.64) with no aseptic revisions during the follow-up period. Progressive tibial RLLs were present in 3.4% of patients at two-years follow-up, but were all less than 2 mm with all combined RLLs less than 4 mm. The FJS-12 and OKS all significantly (p < 0.0001) increased and exceeded their respective minimal clinical important differences, and 93% of patients were satisfied at two-years follow-up.

CONCLUSION

This study supports excellent survivorship, clinical and patient reported outcomes using cementless, fixed bearing TKA with minimal complications at early follow-up. Further follow-up is necessary to confirm the sustainability of the clinical outcomes and to evaluate mid- to long-term survivorship.

Cementless Total Knee Arthroplasty Using an Ultraconforming Tibial Bearing: Outcomes at Minimum 5-Year Follow-Up

BACKGROUND

Cementless fixation for primary total knee arthroplasty (TKA) continues to increase in the United States. However, compared to cemented TKA, reports on revision rates have been mixed. A confounding variable may include the tibial insert design. This study aimed to assess the minimum 5-year survivorship and outcomes of a cementless TKA using an ultracongruent (UC) articulation.

METHODS

A consecutive series of 242 cementless TKAs were implanted at two institutions between 2017 and 2019 using an UC kinematic tibial insert. Of the patients, 56% were men. The average age was 60 years. Patients were followed using Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) and Knee Society clinical and radiographic scores. Preoperative and postoperative radiographs were classified according to the Coronal Plane Alignment of the Knee (CPAK) type. The average follow-up was 5.6 years (range, five to 7.5).

RESULTS

At the final follow-up, KOOS-JR scores averaged 84.0. Knee Society scores averaged 94. Flexion averaged 116°. There were seven manipulations (2.9%), one patella fracture, and no deep infections. There were seven knees (2.9%) revised (three for flexion instability, one for pain, one for femoral fibrous ingrowth, one for distal femur fracture, and one for arthrofibrosis). At 5 years, survivorship free from aseptic loosening was 99.6%. Change in CPAK type did not correlate with final KOOS-JR, pain, University of California Los Angeles activity score, or satisfaction scores.

CONCLUSIONS

Cementless TKA using this conforming design has provided excellent clinical results out to 5 years. Once initial component stability is achieved, the UC nature of this articulation does not appear to adversely influence the durability of implant fixation, regardless of whether the CPAK type was changed.

Selective Use of Modern Cementless Total Knee Arthroplasty is Not Associated with Increased Risk of Revision in Patients Aged 65 or Greater: An Analysis from the American Joint Replacement Registry

Modern highly porous surfaces have increased confidence and use of cementless total knee arthroplasty (TKA) in the United States. As cementless TKA use increases, there remains a paucity of literature regarding associated risk of revision in patients aged ≥65 years. We analyzed the American Joint Replacement Registry (AJRR) data from January 2012 to March 2020 identifying patients aged ≥65 years undergoing primary TKA with linked cases to supplemental centers for Medicare and Medicaid data. Patients with hybrid fixation, reverse hybrid fixation, missing component data, highly constrained implants, and stem extension/augmentation were excluded. We identified 442,745 cemented TKAs and 19,841 modern cementless TKAs with a minimum of 2-year follow-up. Cumulative incident function (CIF) curves and cause-specific Cox models evaluated the risk of all-cause revision and revision for mechanical loosening, adjusting for body mass index (BMI), sex, age, cruciate retaining (CR) versus posterior stabilized (PS) femoral design, patellar resurfacing, and Charlson's comorbidity index (CCI). Patients with cementless compared with cemented TKA were younger (mean age: 71.9 vs. 73.2 years, p < 0.001), more likely to be male sex (48.8 vs. 39.0%, p < 0.001), more likely to have a CR femoral design (81.1 vs. 45.7%, p < 0.001), less likely to have patellar resurfacing (92.7 vs. 95.0%, p < 0.001), and had a lower CCI (mean: 2.9 vs. 3.1, p < 0.001). Adjusted hazard ratios (HRs) showed no difference in associated risk for all-cause revision (HR: 1.07; 95% confidence interval [CI]: 0.92-1.24; p = 0.382) or revision for mechanical loosening (HR: 1.38; 95% CI: 0.9-2.12; p = 0.14) for cementless versus cemented TKA. Our results suggest that current selective use of cementless fixation for TKA in patients aged ≥65 years in the United States is not associated with an increased risk of revision. While encouraging, further study is necessary to establish indications for use in this age group prior to broader adoption in this patient population. LEVEL OF EVIDENCE:  Therapeutic Level III.

Uncemented Total Knee Arthroplasty is on the Rise. A Report of Patient Demographics and Short-Term Outcomes From the Michigan Arthroplasty Registry Collaborative Quality Initiative

Background

Cemented total knee arthroplasty (TKA) is the gold standard treatment for osteoarthritis, but uncemented TKA offers benefits like improved osseointegration and reduced complications from cement debris. This study aimed to investigate (1) if there has been a rise in uncemented TKA from 2017 to 2021 and (2) if there are differences in early complications between cemented and uncemented TKA.

Methods

A retrospective data review was performed on the Michigan Arthroplasty Registry Collaborative Quality Initiative database of TKA patients from 2017 to 2021 at 6 hospitals. Patients with revision or partial knee arthroplasty were excluded. Patients were divided into 2 groups: uncemented and cemented. Hybrid and reverse hybrid fixation data were collected for incidence, but not for demographics or complications. All patient demographics and 90-day postoperative events were collected and analyzed.

Results

A retrospective study of 18,749 primary TKAs found that 89.7% were cemented, 9.7% uncemented, and 0.7% hybrid or reverse hybrid. Uncemented patients were younger, men, heavier, current smokers, and diabetics than cemented patients (P < .0001, P = .03). They also had a shorter length of stay (P ≤ .0001) and were on fewer preoperative medications: anticoagulants (P = .0059), antiplatelets (P ≤ .0001), opioids (P = .0091), and steroids (P = .0039). The rate of uncemented TKA increased from 3.3% to 17.1%, while the rate of cemented TKA fell from 96.2% to 81.9% (P = .0048). The readmission rate was higher in cemented TKAs (4.0%) than in uncemented TKAs (2.6%) (P = .0048).

Conclusions

The use of uncemented TKA increased from 3.3% in 2017 to 17.1% in 2021, while cemented fixation decreased from 96.7% to 81.9%. There were no significant differences in short-term complications between groups. Uncemented patients were younger, men, took fewer medications, had a shorter length of stay, and were less likely to be readmitted. However, they were more likely to have comorbidities than the cemented group.

Comparison of Cemented and Cementless Fixation in Total Knee Arthroplasty: A Meta-Analysis and Systematic Review of RCTs

OBJECTIVE

This study aimed to compare infection, aseptic loosening, revision, operation time, function scores, and the radiographic radiolucent line (RLL) between cementless and cemented fixation in total knee arthroplasty (TKA).

METHODS

Articles reporting the outcomes of cemented and cementless TKA were searched in Medline, EMBASE, Web of Science, and the Cochrane Library. The search was conducted from articles published from January 1996 to May 2024. Odds Ratios (OR) and confidence intervals (CI) were used to measure the results. Cochrane Collaboration's Review Manager software was used to perform the meta-analysis.

RESULTS

Sixteen randomized controlled trials containing 2358 participants were included in this meta-analysis. Pooled data found that, in TKA, there were no significant differences between cemented fixation and cementless fixation for a prosthesis in infection, aseptic loosening and revision. The subgroup analysis and sensitivity analysis results of the knee society score (KSS) showed a significant difference favoring cementless fixation in a follow-up of less than 5 years (MD = -2.30, 95%CI -3.85 -0.74, p = .001) while favoring cemented fixation in a follow-up over 5 years (MD = 2.79, 95%CI 0.95 4.63, p = .003). The operation time of cementless was less than that of cemented (MD = 12.03, 95%CI 8.30 15.77, p < .00001). No significant difference was detected in knee society function score, Western Ontario and McMaster Universities osteoarthritis index, and RLL. There was no heterogeneity across studies (p > .1), and most studies have a low risk of bias.

CONCLUSIONS

Within a follow-up period of less than 5 years, cementless TKA had better KSS, while over 5 years, KSS was better in cemented TKA, and cementless TKA required less operation time.

Cementless Total Knee Arthroplasty: A Resurgence-Who, When, Where, and How?

BACKGROUND

Total knee arthroplasty (TKA) is one of the most common procedures in orthopaedics, but there is still debate over the optimal fixation method for long-term durability: cement versus cementless bone ingrowth. Recent improvements in implant materials and technology have offered the possibility of cementless TKA to change clinical practice with durable, stable biological fixation of the implants, improved operative efficiency, and optimal long-term results, particularly in younger and more active patients.

METHODS

This symposium evaluated the history of cementless TKA, the recent resurgence, and appropriate patient selection, as well as the historical and modern-generation outcomes of each implant (tibia, femur, and patella). Additionally, surgical technique pearls to assist in reliable, reproducible outcomes were detailed.

RESULTS

Historically, cemented fixation has been the gold standard for TKA. However, cementless fixation is increasing in prevalence in the United States and globally, with equivalent or improved results demonstrated in appropriately selected patients.

CONCLUSIONS

Cementless TKA provides durable biologic fixation and successful long-term results with improved operating room efficiency. Cementless TKA may be broadly utilized in appropriately selected patients, with intraoperative care taken to perform meticulous bone cuts to promote appropriate bony contact and biologic fixation.

Cementless, Cruciate-Retaining Primary Total Knee Arthroplasty Using Conventional Instrumentation: Technical Pearls and Intraoperative Considerations

Background

Total knee arthroplasty (TKA) is commonly indicated for patients with severe tibiofemoral osteoarthritis in whom nonoperative treatment has failed. TKA is one of the most commonly performed orthopaedic surgical procedures in the United States and is associated with substantial improvements in pain, function, and quality of life1-3. The procedure may be performed with cemented, cementless, or hybrid cemented and cementless components4,5. Cementless TKA utilizing contemporary implant designs has been demonstrated to have excellent long-term survival and outcomes in patients who are appropriately indicated for this procedure5-8. The preference of the senior author is to perform this procedure with use of a cruciate-retaining implant design when feasible, and according to the principles of mechanical alignment to guide osseous resection. It should be noted that nearly all recent studies on outcomes following cementless TKA utilize traditional mechanical alignment7-9. Alternative alignment strategies, such as gap balancing and kinematic alignment, have not been as well studied in cementless TKA; however, preliminary short-term studies suggest comparable survivorship with restricted kinematic alignment and gap balancing compared with mechanical alignment in patients undergoing cementless TKA10,11.

Description

Our preferred surgical technique for cementless TKA begins with the patient in the supine position. A thigh tourniquet is applied, and a valgus post is set at the level of the tourniquet. A flexion pad is also placed at 90°, with a bar at 20°. After sterile skin preparation and draping, a time-out is conducted, and the tourniquet is raised. The surgeon makes a medial parapatellar incision, which begins from 1 cm medial to the medial edge of the patella, extending from the tibial tubercle to 2 fingers above the proximal pole of the patella, using a knife and with the knee at 90° of flexion. Scissors are then used to find the fat above the fascia and dissect distally in the same plane. A knife is used to perform a high vastus-splitting, medial parapatellar arthrotomy. Pickups and scissors are then used to perform a partial medial synovectomy, and electrocautery is used to perform a medial peel. As the procedure progresses further medial, the infrapatellar fat pad is excised, followed by the anterior femoral synovial tissue. The surgeon then cuts through the anterior cruciate ligament footprint and origin with the knee flexed before sawing through the tibial spines to decrease the height of the tibial bone block. To prepare the femur, a step drill is inserted into the femoral canal, and the intramedullary alignment guide is placed with the distal femoral cutting guide set to 5° of valgus. The distal femoral cutting guide is then pressed firmly against the distal femur, making sure that the medial side is touching bone, and threaded pins are inserted in the cutting guide under power. The distal femur is then precisely sectioned with use of an oscillating saw equipped with a 21 mm x 90 mm x 1.27-mm saw blade. The surgeon focuses on initiating the cut at the cortices before proceeding further, to avoid cortical blow-out. The resultant cut is meticulously assessed for uniformity and levelness, employing both the alignment rod and the distal cutting guide for verification. Following this assessment, the pins and guide are removed, and any remaining femoral condylar osteophytes are delicately excised with use of a rongeur. The surgeon uses the femoral sizing guide, measures the size of the femur, and double-checks rotation in preparation for the remaining distal femoral cuts. The holes are then drilled to set the rotation for the 4-in-1 cutting guide. When applying the 4-in-1 cutting guide, care is taken to align the guide with the drilled holes in order to avoid inadvertent malrotation. The secure fixation of the block is ensured through the judicious insertion of 2 threaded pins under power at full speed, followed by a more controlled, slower securing process to avoid stripping the threaded pins. Subsequently, the anterior cut is made with the oscillating saw, again with a focus on initiating the cut at the cortices before proceeding further. The posterior cuts are then made in a controlled manner, employing a gentle bouncing technique to facilitate tactile feedback, and keen attention is given to cutting both the medial and lateral cortices of each of the posterior condyles. The anterior chamfer and posterior chamfer are similarly osteotomized. Subsequently, the 4-in-1 cutting guide is gently removed. To complete this phase of the procedure, a curved osteotome and mallet are employed to delicately extract the resected posterior condyles and remove posterior osteophytes as needed. The concave side of the curved osteotome is used with precision to meticulously trace the contours of the condyles, ensuring a precise result. The surgeon places a bump under the knee and extends it to check the medial collateral ligament, quadriceps tendon, patellar tendon, and posterior cruciate ligament to ensure they are intact. To make the tibial cut, the extramedullary alignment guide is placed, and the height of the slot is set to the level of the subchondral bone, aligning the rotation and coronal axis with the 2nd metatarsal. The tibial slope is also set at this step, with the goal of the resection matching the patient's native tibial slope. Matching is usually achieved by visual inspection of the trajectory of the cutting jig, although the stylus can also be utilized to confirm the appropriate tibial slope. The tibial cut is then completed with use of an oscillating saw. A single-sided reciprocating saw is then used to cut perpendicular to the plateau in the medial compartment while making sure not to extend the cut into the unresected portion of the intact tibial plateau. After removal of the medial plateau fragment, a lamina spreader is placed in the medial compartment; this process is repeated with a second cut in a similar fashion in the lateral compartment to create a triangular bone block that fully preserves the insertion of the posterior cruciate ligament. The medial and lateral menisci are resected, and the gaps are checked with use of a spacer block and alignment rod. The surgeon then sizes the tibia and uses their index fingers to feel both medially and laterally for overhang. An alternative approach is to fully expose the tibia in flexion and to size the tibia under complete visualization of the tibial margins. The tibial trial is then pinned in place after ensuring appropriate external rotation and optimal tibial coverage without overhang. The femoral and tibial trial components are placed, and the surgeon tests 7 things: (1) overall varus-valgus alignment in full extension; (2) degree of extension (specifically noting any amount of recurvatum or flexion contracture); (3) flexion to gravity; (4) anteroposterior stability in flexion (using manual anterior-posterior translation of the tibia); (5) varus-valgus stability in extension, mid-flexion, and full flexion with use of a manual dynamic varus-valgus stress test; (6) patellar tracking; and (7) component rotation. At this point, if any of the above checkpoints are not within acceptable tolerances, additional ligamentous releases or cuts may be performed. After the surgeon is satisfied with the positioning and stability of the trial components, the tibial preparation is completed by seating the feet of the tibial bushing into the tray and drilling the tibia, then punching out the keel. The pins and the tray are removed, the retractors are taken out, and the knee is extended. The surgeon then performs a pulse lavage of the femur and tibia with normal saline solution. The final components are opened, attached to the inserters, and placed in plastic coverings. The final tibial baseplate is inserted and impacted, followed by the femoral component in a similar fashion. We ensure that no soft tissue is incarcerated under the components after impaction. A trial bearing is placed, and the knee is extended. The joint space is then bathed in approximately 500 mL of sterile 0.35% povidone-iodine solution, followed by pulsatile lavage with 1 L of sterile isotonic sodium chloride solution without antibiotics. Stability is then tested again, testing the (7) checkpoints previously discussed. At this point, the only modification that can be made is an increase or decrease in the polyethylene component. Our belief is that any additional changes that require removal or repositioning of the previously implanted cementless femoral and tibial components warrant modification to the cemented TKA. Once satisfied with the stability of the real implants and the trial tibial articular surface, the final polyethylene component is inserted. Finally, the tourniquet is released. The surgeon then irrigates the wound again and closes the arthrotomy and skin. Our preference is to utilize a knotless barbed suture for the arthrotomy closure, followed by 2-0 Vicryl (Ethicon) for subcutaneous closure and 2-0 monofilament knotless barbed suture for skin closure. Some surgeons may choose to utilize a non-barbed suture; however, the use of a barbed suture has been shown to be faster and equally as effective as a non-barbed suture in a large meta-analysis of patients undergoing TKA12. Before final closure, the peri-incisional iodophor-impregnated antimicrobial incise drape is peeled back, and sterile 10% povidone-iodine is applied to the skin surrounding the incision. After subcuticular closure, adhesive skin glue is applied, followed by a waterproof dressing with the knee in flexion.

Alternatives

There are numerous nonoperative treatments available for tibiofemoral osteoarthritis. According to the 2021 American Academy of Orthopaedic Surgeons Management of Osteoarthritis of the Knee (Non-Arthroplasty) Clinical Practice Guideline, these include bracing, nonsteroidal anti-inflammatory drugs, acetaminophen, supervised exercise, patient education, weight loss, and intra-articular corticosteroid injection, among others13. When nonoperative treatment has failed, surgical treatment is then indicated for patients who continue to have symptoms that interfere with quality of life. Surgical treatments for tibiofemoral osteoarthritis primarily include unicompartmental knee arthroplasty or TKA, although proximal tibial osteotomy can be performed in some select cases according to disease severity and patient age. Each of these treatments is supported by the recent 2022 American Academy of Orthopaedic Surgeons Management of Osteoarthritis of the Knee (Non-Arthroplasty) Clinical Practice Guideline.

Rationale

Historically, the initial generation of cementless TKA implant designs was associated with relatively high rates of failure and poor clinical outcomes when compared with cemented arthroplasty14,15. However, there has been a renewed interest in cementless TKA with modern implant designs that incorporate newer biomaterials and porous coatings, with several recent studies demonstrating equivalence to cemented components at short-term, mid-term, and in some studies long-term follow-up4,6-8. In a recent study, Kim et al. demonstrated 98% survival free from revision for aseptic loosening at 22 to 25 years postoperatively7. In addition to at least equivalent long-term functional outcomes compared with cemented TKA, across multiple studies4,7, several short-term benefits of cementless fixation have been reported, including decreased costs and the avoidance of complications associated with cement debris8,16,17. Additionally, because there is no need to mix cement, there is a reduced burden of staff training and the elimination of possible variables that may affect cement integrity, in turn leading to improved operative efficiency and shorter operative time8. Bone cement implantation syndrome (BCIS) has been reported in up to 28% of cases of cemented TKA, and has a substantial risk of morbidity and mortality16. Cement debris can also remain in the knee if not retrieved after cement curing and prior to closure17, which is believed to cause discomfort and polyethylene wear. This complication is also avoided when cementless implants are utilized. Additional factors leading to our preference for cementless TKA, when indicated, have not yet been proven in the literature but are intuitive concepts. For example, the lack of cement leads to easier removal of components during revision surgery, and preservation of bone stock is important for performing a successful revision TKA.

Expected Outcomes

Cementless TKA using modern implant designs has excellent long-term outcomes at up to 25 years. Kim et al. evaluated 261 patients who underwent bilateral simultaneous TKA with random assignment of cemented and cementless components in contralateral knees. In that study, the mean age was 63 years and the mean follow-up was 24 years. The authors found 98% survival without revision for aseptic loosening at 25 years7. Similar findings have also been shown in older patients. For example, in a 2022 study by Goh et al., 7-year survivorship of modern implant designs was 100%. In that study of patients >75 years old, 120 cementless TKAs were matched in a 1:3 ratio with TKAs using cemented implants of the same modern design. Ultimately, no difference was seen in final postoperative scores or improvement in scores at 2 years. Seven-year survivorship free from aseptic revision was 99.4% for patients with cemented implants and 100% for patients with cementless implants4.

Important Tips

When deciding to perform cementless TKA, we consider a variety of preoperative factors, such as a history of osteoporosis, preoperative radiographs showing areas of bone loss, and a history of conditions associated with low bone mineral density.Intraoperative factors can also be considered when deciding between cementless and cemented implants. For example, tactile feedback when sawing can help to determine if bone is hard and sclerotic, which we believe indicates a better candidate for cementless implants.○ Note that during tibial preparation in a varus knee, you will typically have substantial sclerosis of the medial tibial plateau and relative osteopenia in the lateral tibial plateau because of longstanding differences in joint loading. This pattern is reversed in valgus knees.○ In general, we believe that the decision regarding bone integrity should be made primarily on the basis of the non-sclerotic side.With use of the techniques described in the present article, we do not have a preoperative alignment threshold or knee range-of-motion criteria for cementless TKA. More research is needed, however, on the long-term outcomes of cementless TKA when utilizing personalized alignment strategies, which may dictate the placement of components in substantial varus or valgus relative to the anatomic axis.When utilizing keeled tibial implants, we recommend drilling in reverse to pack the walls of the drill hole with bone rather than milling it out, which we believe increases support for bone growth.If there is almost no resistance while drilling in reverse, we believe this to be a poor prognostic sign for cementless TKA, and cementing should be considered.When sizing the tibial baseplate, the goal is to maximize the size of the tibia to fit on top of the rim of cortical bone without overhanging. Undersizing may increase the potential for implant subsidence.Osseous cuts with cementless components need to be perfect. Dome-shaped cuts are at risk for rocking and/or toggling, which could contribute to loosening over time.All 4 quadrants of the tibia should be checked to confirm a flat surface.Soft tissues can get incarcerated under the implant, which is of particular concern for cementless implants as this could impair osseous ingrowth.During trialing, ensure that the trial is completely flush on bone, which is an additional check to guard against toggling and/or loosening.When impacting the femoral component, we recommend applying an extension force so that the weight of the inserter does not pull the component into flexion; however, excessive extension force could also cause a fracture.

Acronyms and Abbreviations

IV = intravenousAP = anteroposterior.

Cementless Total Knee Arthroplasty: A State-of-the-Art Review

» The demographic profile of candidates for total knee arthroplasty (TKA) is shifting toward younger and more active individuals.» While cemented fixation remains the gold standard in TKA, the interest is growing in exploring cementless fixation as a potentially more durable alternative.» Advances in manufacturing technologies are enhancing the prospects for superior long-term biological fixation.» Current research indicates that intermediate to long-term outcomes of modern cementless TKA designs are comparable with traditional cemented designs.» The selection of appropriate patients is critical to the success of cementless fixation techniques in TKA.» There is a need for high-quality research to better understand the potential differences and relative benefits of cemented vs. cementless TKA systems.

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.