Cementless vs Cemented Tibial Fixation in Primary Total Knee Arthroplasty

Comparison of Postoperative Outcomes of Patients Undergoing Total Hip and Total Knee Arthroplasty Following a Diagnosis of Dementia: A TriNetX Database Study

Background

As life expectancy improves for patients with dementia, the demand for mobility-improving surgeries such as total joint arthroplasty (TJA) will increase. There is little research on patients with dementia undergoing TJA, although dementia has been shown to be a risk factor for complications. The purpose of this study is to compare postoperative outcomes of patients with dementia undergoing TJA at 90 days, 2 years, and 5 years.

Methods

The TriNetX database was retrospectively queried for all patients undergoing total hip arthroplasty (THA) and total knee arthroplasty (TKA). Patients were divided into cohorts by preoperative diagnosis of dementia and propensity score matched. The following outcomes were evaluated between groups at 90 days, 2 years, and 5 years postoperatively: revision, resection arthroplasty, closed reduction (THA only), femur fracture plating, and prosthetic joint infection. Readmission and manipulation under anesthesia (TKA only) were evaluated at 90 days postoperatively. Univariate and multivariate analyses were performed.

Results

After matching, there were no differences in demographics or comorbidities between groups. TKA (odds ratio [OR] = 1.75, 95% confidence interval [CI] 1.42-2.15, P < .001) and THA (OR = 2.17, 95% CI 1.92-2.45, P < .001) patients with dementia were more likely to be readmitted than patients without dementia. At 2 years (OR = 2.07, 95% CI 1.14-3.77, P = .015) and 5 years (OR = 2.14, 95% CI 1.32-3.48, P = .002) postoperatively, THA patients with dementia were more likely to have proximal femur fracture plating than patients without dementia.

Conclusions

Patients undergoing THA with dementia had worse outcomes than patients undergoing THA without dementia and TKA with dementia. The overall rate of complications was low, and a diagnosis of dementia should not be an absolute contraindication to proceeding with TJA.

No component loosening of a cementless deep dish rotating platform knee at a 5-year follow-up

PURPOSE

Cemented fixation remains the gold standard in total knee arthroplasty. With an increasing number of younger patients undergoing total knee arthroplasty and a growing patient population demanding higher physical activity, a rising interest in discussion of cementless fixation is notable. The current scientific literature does not give a clear recommendation for or against uncemented total knee arthroplasty. The purpose of this study was the investigation of the 5-year clinical and radiographic outcomes of a cementless deep-dish rotating platform implant.

METHODS

A total of 91 primary cementless total knee arthroplasties were included in this single-centre prospective observational study. The primary outcome was revision rate due to aseptic component loosening. Further outcome measures were assessment of the of the radiographic outcome as well as the clinical outcome based on Range of Motion and scores such as American Knee Society Score, Oxford Knee Score, Knee Injury and Osteoarthritis Outcome Score and European Quality of Life 5 Dimension 3 Level at a follow-up of 5 years.

RESULTS

Mean age of the study population was 67.3 ± 6.6 years with 49.5% of the participants being female. Aseptic component loosening occurred in none of the patients. Implant survival with revision for any reason as endpoint was 97.8% (95% CI 100-96%) and 95.6% (95% CI 100-94%) with reoperation of any cause as endpoint. Radiolucent lines were detected in a total of eight cases (8.8%) and disappeared within the first year after surgery in five cases. Total Range of Motion improved significantly from 106° ± 15° preoperatively to 118° ± 10° at final FU (p < 0.001). All investigated scores improved significantly after total knee arthroplasty.

CONCLUSION

The results of this study reveal excellent mid-term performance of a cementless deep dish rotating platform total knee implant, with no component loosening, very low overall revision rate, only temporarily present radiolucent lines in a minority of patients and excellent clinical results. Therefore, cementless total knee arthroplasty is an appropriate treatment option for patients with severe osteoarthritis of the knee.

LEVEL OF EVIDENCE

Level II (prospective cohort study).

Mid-Term Performance of the First Mass-Produced Three-Dimensional Printed Cementless Tibia in the United States as Reported in the American Joint Replacement Registry

BACKGROUND

Cementless tibial components have shown improvements in clinical performance compared to predicate designs, though evidence supporting mid-term performance and fixation is scarce. The purpose of this study is to determine the mid-term survivorships, revision rates, and reasons why 3-dimensional printed cementless tibial baseplates (3DTKAs) failed compared to other cementless as well as cemented tibial baseplates reported from the American Joint Replacement Registry (AJRR) data.

METHODS

All primary total knee arthroplasty (TKA) cases performed in patients 65 years of age or older within the AJRR from January 2, 2012 through June 30, 2020 were queried. A total of 28,631 3DTKAs were identified from 428 institutions. These were compared to all other "aggregated cementless tibia" (n = 7,577) and "aggregated cemented tibia" (n = 550,133) cases. Centers for Medicare & Medicaid Services data over the same time period were merged with AJRR data to determine survivorship and patient-timed incident revision rates per 1,000 years. Failure reasons were tracked during this study period.

RESULTS

At 60 months, Kaplan-Meier implant survivorship was 98.9% (CI 98.7-99.0), 98.3% (CI 97.9-98.6), and 98.4% (CI 98.4-98.5) in the 3DTKA, aggregate cementless, and cemented knee cohorts, respectively (P < .0001). Patient-timed incident revision rates were 3.11 (CI 2.75-3.53), 3.99 (CI 3.34-4.76), and 3.35 (CI 3.28-3.42) for those cohorts, which corresponds to a revision rate of 0.31%, 0.40%, and 0.34% per year.

CONCLUSION

In this analysis, 3DTKA had favorable survivorship and lower revision rates compared to aggregate cementless and cemented TKAs implanted from the same national database during the same time period.

Short-term results of the uncemented triathlon total knee arthroplasty: a large cohort single-centre comparative study

BACKGROUND

The purpose of this study is to assess the short-term survivorship of a new uncemented TKA design in a high-volume centre to evaluate the safety of this design prior to widespread adoption.

METHODS

We performed a retrospective cohort study of all primary TKAs (cemented and uncemented) between May 2018 and May 2019. Primary outcome variables included aseptic revision, all-cause revision, time to revision, operative time and radiological outcomes. Predictor variables considered included age, gender, BMI, ASA, implant type (cruciate-retaining, posterior-stabilised or totally-stabilised) and the use of cemented or uncemented implants.

RESULTS

There were 300 cemented TKAs and 249 uncemented TKAs (Triathlon, Stryker Inc., Mahwah, NJ) implanted. The mean follow-up for all cases was 31.6 months (minimum follow-up 2 years). Of the entire 549 implants only 4 were revised. Two of these were for infection, 1 was for patellar maltracking and 1 was for knee stiffness. All 4 revisions occurred in the cemented cohort. The aseptic revision rate in the cemented cohort was 0.7% compared to 0.0% in the uncemented cohort (p = 0.298). Operative times were significantly reduced in the uncemented cohort from 57.9 to 51.7 min (p < 0.001). There were 8/300 (2.6%) patients with RLLs in the cemented cohort and 4/249 (1.6%) patients with RLLs in the uncemented cohort (p = 0.56).

CONCLUSION

The uncemented Triathlon TKA demonstrates excellent survivorship at short-term follow-up when compared to the cemented Triathlon TKA, thus eliminating any potential clinical concerns with this novel implant in the early post-operative phase.

A Novel Nanostructured Surface on Titanium Implants Increases Osseointegration in a Sheep Model

BACKGROUND

A nanostructured titanium surface that promotes antimicrobial activity and osseointegration would provide the opportunity to create medical implants that can prevent orthopaedic infection and improve bone integration. Although nanostructured surfaces can exhibit antimicrobial activity, it is not known whether these surfaces are safe and conducive to osseointegration.

QUESTIONS/PURPOSES

Using a sheep animal model, we sought to determine whether the bony integration of medical-grade, titanium, porous-coated implants with a unique nanostructured surface modification (alkaline heat treatment [AHT]) previously shown to kill bacteria was better than that for a clinically accepted control surface of porous-coated titanium covered with hydroxyapatite (PCHA) after 12 weeks in vivo. The null hypothesis was that there would be no difference between implants with respect to the primary outcomes: interfacial shear strength and percent intersection surface (the percentage of implant surface with bone contact, as defined by a micro-CT protocol), and the secondary outcomes: stiffness, peak load, energy to failure, and micro-CT (bone volume/total volume [BV/TV], trabecular thickness [Tb.Th], and trabecular number [Tb.N]) and histomorphometric (bone-implant contact [BIC]) parameters.

METHODS

Implants of each material (alkaline heat-treated and hydroxyapatite-coated titanium) were surgically inserted into femoral and tibial metaphyseal cancellous bone (16 per implant type; interference fit) and in tibial cortices at three diaphyseal locations (24 per implant type; line-to-line fit) in eight skeletally mature sheep. At 12 weeks postoperatively, bones were excised to assess osseointegration of AHT and PCHA implants via biomechanical push-through tests, micro-CT, and histomorphometry. Bone composition and remodeling patterns in adult sheep are similar to that of humans, and this model enables comparison of implants with ex vivo outcomes that are not permissible with humans. Comparisons of primary and secondary outcomes were undertaken with linear mixed-effects models that were developed for the cortical and cancellous groups separately and that included a random effect of animals, covariates to adjust for preoperative bodyweight, and implant location (left/right limb, femoral/tibial cancellous, cortical diaphyseal region, and medial/lateral cortex) as appropriate. Significance was set at an alpha of 0.05.

RESULTS

The estimated marginal mean interfacial shear strength for cancellous bone, adjusted for covariates, was 1.6 MPa greater for AHT implants (9.3 MPa) than for PCHA implants (7.7 MPa) (95% CI 0.5 to 2.8; p = 0.006). Similarly, the estimated marginal mean interfacial shear strength for cortical bone, adjusted for covariates, was 6.6 MPa greater for AHT implants (25.5 MPa) than for PCHA implants (18.9 MPa) (95% CI 5.0 to 8.1; p < 0.001). No difference in the implant-bone percent intersection surface was detected for cancellous sites (cancellous AHT 55.1% and PCHA 58.7%; adjusted difference of estimated marginal mean -3.6% [95% CI -8.1% to 0.9%]; p = 0.11). In cortical bone, the estimated marginal mean percent intersection surface at the medial site, adjusted for covariates, was 11.8% higher for AHT implants (58.1%) than for PCHA (46.2% [95% CI 7.1% to 16.6%]; p < 0.001) and was not different at the lateral site (AHT 75.8% and PCHA 74.9%; adjusted difference of estimated marginal mean 0.9% [95% CI -3.8% to 5.7%]; p = 0.70).

CONCLUSION

These data suggest there is stronger integration of bone on the AHT surface than on the PCHA surface at 12 weeks postimplantation in this sheep model.

CLINICAL RELEVANCE

Given that the AHT implants formed a more robust interface with cortical and cancellous bone than the PCHA implants, a clinical noninferiority study using hip stems with identical geometries can now be performed to compare the same surfaces used in this study. The results of this preclinical study provide an ethical baseline to proceed with such a clinical study given the potential of the alkaline heat-treated surface to reduce periprosthetic joint infection and enhance implant osseointegration.

Trabecular metal monoblock versus modular tibial trays in total knee arthroplasty: meta-analysis of randomized control trials

PURPOSE

Total knee arthroplasty is one of the significantly evolving procedures with different knee designs available in the market. The continued development of these prosthesis resulted in improvement of the implant survivorship and patient satisfaction. This study is an RCT-based meta-analysis aimed to compare two designs of total knee replacement: the conventional modular and the monoblock trabecular metal tibial trays.

METHODS

This meta-analysis was performed by a literature review according to the PRISMA guidelines. A detailed search of the English literature was done using the PubMed, Medline, CINAHL, Cochrane, Embase, and Google Scholar databases. Only randomized control trials were included in the analysis after ensuring homogeneity. RevMan V.5.0.18.33 (The Cochrane Collaboration, Copenhagen, Denmark) was used to perform the meta-analysis. Extracted outcome measures were Knee Society score, Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) score, survivorship, complication rate, and radiostereographic analysis.

RESULTS

Seven randomized control trials with 635 patients were eligible for our analysis after they met our inclusion criteria. Three hundred twelve patients received monoblock tibias, and the other 323 patients received modular tibial trays during their total knee arthroplasty surgeries. There were statistically significant superiority of the modular knees in the functional Knee Society and WOMAC scores at five years (P = 0.003 and 0.05, respectively). The modular design was also more stable on RSA at two years (P < 0.0001).

CONCLUSION

Modular and monoblock tibial trays are comparable knee designs with comparable survivorship and complication rates. However, the modular knees had better mid-term functional outcome and are more stable on radiostereographic analysis.

The Impact of Component Design and Fixation on Stress Shielding After Modern Total Knee Arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) tibial baseplate thickness, metallurgy, and implant fixation with cement may influence stress shielding. The purpose of the present study is to compare bone mineral density of 2 cemented and press-fit TKA designs with differing tibial baseplate thicknesses and metallurgy over a 2-year period to assess for changes in stress shielding.

METHODS

One-hundred one TKAs were performed in this Institutional Review Board-approved, prospective study. There were 4 cohorts: DePuy Attune cemented and press-fit, and Stryker Triathlon cemented and press-fit. The Attune tibial baseplate was thicker; both cemented tibial and femoral components were cobalt-chromium. The DePuy Attune press-fit had a cobalt-chromium sintered bead porous coating while the Stryker Triathlon was 3-dimensional printed highly porous titanium alloy. All patients had quantitative dual-energy X-ray absorptiometry scans performed at baseline (4-6 weeks postoperatively) and at 1 and 2 years postoperatively. Stress shielding was evaluated by comparing percent change in bone mineral density in 11 radiographic zones over 2 years.

RESULTS

Over a 2-year period, there were no differences in stress shielding on the tibial side in either cemented or press-fit between Stryker Triathlon and DePuy Attune; however, there were differences on the femoral side. The press-fit tibial components of the Stryker Triathlon and DePuy Attune had either similar or less stress shielding over a 2-year period compared to their cemented counterparts.

CONCLUSION

This study comparing 2 TKA implants with differing tibial tray thickness did not find significant differences in tibial stress shielding between designs. There was a difference in stress shielding on the femoral side between designs, suggesting that longer term follow-up is warranted.

Ultra-Pulsed CO2 Laser Osteotomy: A New Method for the Bone Preparation of Total Knee Arthroplasty

Cementless total knee arthroplasty (TKA) can achieve long-term biological fixation, but its application is limited by the risk of early aseptic loosening. One of the important reasons for early aseptic loosening is that mechanical osteotomy tools cannot achieve ideal bone preparation because of poor accuracy and serious bone tissue damage produced by them. Therefore, we designed an ultra-pulsed CO₂ laser osteotomy system to solve these problems. To reveal the safety at the tissue and cell levels of the ultra-pulsed CO₂ laser osteotomy system, a series of experiments on distal femur osteotomy in animals were performed. Then, the bone surface characteristics were analyzed through scanning electron microscopy, and the bone thermal and mechanical damage was evaluated via histological analysis. Finally, mesenchymal stem cells (MSCs) were inoculated on the bone surfaces prepared by the two osteotomy tools, and the effect of cell adhesion was analyzed through a confocal laser scanning microscope (CLSM). We successfully achieved TKA bone preparation of animal knees with the ultra-pulsed CO₂ laser osteotomy system. Moreover, the biological evaluation results indicated that compared with the traditional mechanical saw, the laser can preserve the natural bone structure and cause no thermal damage to the bone. In addition, CLSM examination results showed that the laser-cut bone surface was more conducive to cell adhesion and infiltration than the bone surface cut by a mechanical saw. Overall, these results indicate that ultra-pulsed CO₂ laser can achieve non-invasive bone cutting, which can be a new option for TKA bone preparation and has the potential to lead in the future.

Restricted kinematic alignment leads to uncompromised osseointegration of cementless total knee arthroplasty

PURPOSE

While kinematic alignment (KA) total knee arthroplasty (TKA) with cemented implants has been shown to provide equivalent or better results than mechanical alignment, its combination with cementless fixation has not yet been documented. The purpose of this study is to report (1) revision rate and causes, (2) clinical results based on patient report outcome measures (PROMs), and (3) radiological signs of implant dysfunction in patients with an uncemented TKA implanted with restricted KA (rKA), after a minimum follow-up of 2 years.

METHODS

This study included the first 100 consecutive uncemented cruciate retaining TKAs implanted between November 2015 and February 2018 by a single surgeon following rKA principles. At last follow-up, all adverse events and PROMs assessed by WOMAC, KOOS, and FJS scores were documented. Radiographic evaluation was performed to identify signs of implant loosening.

RESULTS

After a mean follow-up of 49 months (32, 60), no implant revision was performed for aseptic loosening. Three revisions were performed: one for malalignment, one for a deep infection, and one for instability. The mean WOMAC score was 20.1 (0-79, 21.3), the mean KOOS score was 71.5 (19.0-96.6, 19.8), and the mean FJS score was 65.9 (0-100, 29.6). No radiological evidence of implant aseptic loosening or osteolysis was identified.

CONCLUSION

This study shows that in 99% of our cases, rKA combined with the tested cementless TKA implant allowed for adequate secondary fixation and good functional outcomes in the short term. Favourable mid- to long-term implant survivorship is anticipated.

LEVEL OF EVIDENCE

III.

Clinical Course of Pain and Function Following Total Knee Arthroplasty: A Systematic Review and Meta-Regression

BACKGROUND

Total knee arthroplasty (TKA) is widely considered a successful intervention for osteoarthritis and other degenerative knee diseases. This study addresses the need for a high-quality meta-analysis that outlines the clinical course of pain and function post-TKA.

METHODS

The review included prospective cohort studies assessing pain or function of patients undergoing primary TKA at baseline (preoperatively) and at least 2 additional time points including one at least 12 months postoperatively. Two reviewers independently screened references, extracted data, and assessed risk of bias using the Quality in Prognosis Studies tool. The time course of recovery of pain and function was modeled using fractional polynomial meta-regression.

RESULTS

In total, 191 studies with 59,667 patients were included, most with low risk of bias. The variance-weighted mean pain score (/100, 0 = no pain) was 64.0 (95% confidence interval [CI] 60.2-67.7) preoperatively, 24.1 (95% CI 20.3-27.9) at 3 months, 20.4 (95% CI 16.7-24.0) at 6 months, and 16.9 (95%CI 13.6-20.3) at 12 months, and remained low (10.1; 95% CI 4.8-15.4) at 10 years postoperatively. The variance-weighted mean function score (/100, 0 = worst function) was 47.1 (95% CI 45.7-48.4) preoperatively, 72.8 (95% CI 71.3-74.4) at 3 months, 76.3 (95% CI 74.7-77.8) at 6 months, and 78.1 (95%CI 76.4-79.7) at 12 months. Function scores were good (79.7; 95% CI 77.9-81.5) at 10 years postoperatively.

CONCLUSION

Patients undergoing primary TKA can expect a large and rapid but incomplete recovery of pain and function in the first postoperative year. At 10 years, the gains in pain scores may still remain while there is an improvement in function.

Primary Stability in Cementless Rotating Platform Total Knee Arthroplasty

Highly porous ingrowth surfaces have been introduced into tibial tray fixation to improve long-term survivorship in cementless total knee arthroplasty. This study was designed to evaluate the effect of porous ingrowth surface on primary stability in the implanted cementless tibial component. Three tibial tray designs possessing sintered bead or roughened porous coating ingrowth surfaces were implanted into a foam tibia model with primary stability assessed via digital image correlation during stair descent and condylar liftoff loading. Follow-up testing was conducted by implanting matched-pair cadaveric tibias with otherwise identical trays with two iterations of ingrowth surface design. Trays were loaded and micromotion evaluated in a condylar liftoff model. The sintered bead tibial tray exhibited slightly lower micromotion than the roughened porous coating in stair descent loading. However, no significant difference in primary stability was observed in condylar liftoff loading in either foam or cadaveric specimens. Cementless tibial trays featuring two different iterations of porous ingrowth surfaces demonstrated both good stability in cadaveric specimens with less than 80 microns of micromotion and 1 mm of subsidence under cyclic loading. While improved ingrowth surfaces may lead to improved biological fixation and long-term osteointegration, this study was unable to identify a difference in primary stability associated with subsequent ingrown surface design iteration.

Metaphyseal Stem Extension Improves Tibial Stability in Cementless Total Knee Arthroplasty

BACKGROUND

The goal was to determine if the addition of a metaphyseal stem extension limits micromotion of a cementless tibial component during cyclic loading in primary total knee arthroplasty. The hypothesis tested was that the use of a 50-mm stem extension on a cementless tibial component would limit motion compared with an identical cementless component without a stem extension.

METHODS

The study used 3 variations of a tibial component from the same total knee arthroplasty system. Group 1 consisted of a cementless tibial component without a stem extension. Group 2 used the same cementless component as group 1, but with the addition of a short 50-mm stem. Group 3 consisted of a cemented tibial component without a stem extension to serve as a "control" (gold standard). The tibial specimens were implanted into a synthetic bone model and tested using a physiological medial-lateral 60/40 load distribution for 5000 cycles.

RESULTS

The results demonstrated a significant decrease in motion at the anterior region of the cementless stem extension (group 2) components compared with the cementless with no stem extension (group 1). The cementless with stem extension (group 2) demonstrated similar results at all cycles to the cemented (group 3) components at the anterior region.

CONCLUSION

The addition of a short metaphyseal stem (50mm) to a keel plus 4-peg tibial component design provides a significant reduction in micromotion during cyclic loading of a cementless tibial baseplate in a synthetic foam bone model, similar to a cemented implant.

Better outcomes are associated with cementless fixation in primary total knee arthroplasty in young patients: A systematic review and meta-analysis of randomized controlled trials

BACKGROUND

The use of cemented and cementless fixations in primary total knee arthroplasty (TKA) in young patients is controversial. Previous reviews predominantly relied on data from retrospective studies. This systematic review and meta-analysis of randomized controlled trials (RCTs) evaluated the optimal fixation mode in TKA for young patients.

METHODS

The PubMed, Embase, Medline, Web of Science, and full Cochrane Library electronic databases were searched from inception to July 2018. The outcome measurements consisted of functional outcomes (Knee Society Score [KSS], range of motion [ROM]), radiolucent lines, aseptic loosening, total complications, and reoperation rate. Study data were pooled using a random-effects model.

RESULTS

Six RCTs were included in the systematic review and meta-analysis. The mean follow-up period was 12 years (range, 2-16.6 years). Cementless TKA was associated with higher KSS-function (P < .0001), higher KSS-pain (P = .005), better ROM recovery (P = .01), and fewer radiolucent lines (<1 mm) (P = .04) compared with cemented TKA. No significant intergroup differences were observed for KSS-knee, total complications, aseptic loosening, or reoperation rate. These results based on a random-effects model were unchanged by sensitivity analysis assumptions.

CONCLUSION

Cementless TKA was substantially superior to cemented TKA in young patients. Although the complication and survival rates were similar between groups, better clinical outcomes were obtained with cementless fixation. Further well-designed studies with long follow-up durations are necessary to confirm our findings.

Evaluation of the Painful Total Knee Arthroplasty

Total knee arthroplasty (TKA) has been associated with notable improvements in health-related quality of life of patients with end-stage knee arthritis. Although most patients experience substantial symptomatic relief after TKA, up to 19% of patients are unsatisfied with their outcome. With the dramatic, projected increase in the number of TKAs performed annually, it is crucial to appreciate the various modes of failure associated with this procedure. A comprehensive understanding of the symptomatology and thorough clinical examination aid in identifying the etiology of ongoing knee pain. Ancillary testing including conventional laboratory analyses, imaging studies, and diagnostic injections supplement a thorough history and physical examination. In addition, novel laboratory markers, RNA/DNA-based tests, and novel imaging modalities are emerging as beneficial tools in evaluating patients with a painful TKA. A well-structured, algorithmic approach in the management of these patients is essential in correctly diagnosing the patient and optimizing clinical outcomes.

Porous Tantalum and Titanium in Orthopedics: A Review

Porous metal is metal with special porous structures, which can offer high biocompatibility and low Young's modulus to satisfy the need for orthopedic applications. Titanium and tantalum are the most widely used porous metals in orthopedics due to their excellent biomechanical properties and biocompatibility. Porous titanium and tantalum have been studied and applied for a long history until now. Here in this review, various manufacturing methods of titanium and tantalum porous metals are introduced. Application of these porous metals in different parts of the body are summarized, and strengths and weaknesses of these porous metal implants in clinical practice are discussed frankly for future improvement from the viewpoint of orthopedic surgeons. Then according to the requirements from clinics, progress in research for clinical use is illustrated in four aspects. Various creative designs of microporous and functionally gradient structure, surface modification, and functional compound systems of porous metal are exhibited as reference for future research. Finally, the directions of orthopedic porous metal development were proposed from the clinical view based on the rapid progress of additive manufacturing. Controllable design of both macroscopic anatomical bionic shape and microscopic functional bionic gradient porous metal, which could meet the rigorous mechanical demand of bone reconstruction, should be developed as the focus. The modification of a porous metal surface and construction of a functional porous metal compound system, empowering stronger cell proliferation and antimicrobial and antineoplastic property to the porous metal implant, also should be taken into consideration.

Uncemented monoblock trabecular metal posterior stabilized high-flex total knee arthroplasty: similar pattern of migration to the cruciate-retaining design - a prospective radiostereometric analysis (RSA) and clinical evaluation of 40 patients (49 knees) 60 years or younger with 9 years' follow-up

Background and purpose - Uncemented monoblock cruciate retaining (CR) trabecular metal (TM) tibial components in total knee arthroplasty (TKA) work well in the long-term perspective in patients ≤ 60 years. Younger persons expect nearly normal knee flexion after TKA, but CR implants generally achieve less knee flexion compared with posterior stabilized (PS) implants. Cemented PS implants have higher revision rate than CR implants. Can an uncemented monoblock PS TM implant be used safely in younger patients? Patients and methods - 40 patients (49 knees) age ≤ 60 years with primary (20 knees) or posttraumatic osteoarthritis (OA) were operated with a high-flex TKA using an uncemented monoblock PS TM tibial component. Knees were evaluated with radiostereometric analysis (RSA) a mean 3 days (1-5) postoperatively, and thereafter at 6 weeks, 3 months, 1, 2, 5, and 9 years. Clinical outcome was measured with patient-related outcome measures (PROMs). Results - The implants showed a pattern of migration with initial large migration followed by early stabilization lasting up to 9 years, a pattern known to be compatible with good long-term results. Clinical and radiological outcome was excellent with 38 of the 40 patients being satisfied or very satisfied with the procedure and bone apposition to the entire implant surface in 46 of 49 knees. Mean knee flexion was 130°. 1 knee was revised at 3 months due to medial tibial condyle collapse. Interpretation - The uncemented monoblock PS TM implant works well in younger persons operated with TKA due to primary or secondary OA.

Despite Improved Survivorship of Uncemented Fixation in Total Knee Arthroplasty for Osteoarthritis, Cemented Fixation Remains the Gold Standard: An Analysis of a National Joint Registry

BACKGROUND

Total knee arthroplasty (TKA) numbers are increasing worldwide. While cement fixation for both femoral and tibial components is commonly used, alternatives include hybrid and uncemented TKAs. This study aimed to evaluate survivorship, revision rates, and patient-reported outcomes for cemented, hybrid, and uncemented TKAs using New Zealand Joint Registry (NZJR) data.

METHODS

NZJR data relating to all TKAs performed during the 19 years up to the end of December 2017 were analyzed. Outcomes were assessed using prosthesis survivorship data (including reasons for revision) and Oxford scores at 6 months, 5 years, and 10 years postoperatively.

RESULTS

A total 96,519 primary TKAs were performed during the period examined. Most (91.5%) were fully cemented with 4.8% hybrid and 3.7% uncemented. Mean Oxford scores at 6 months were highest in cemented and lowest in uncemented TKAs (P < .001). However, this was not clinically significant. There was no difference at 5 or 10 years. Ten-year survival rates were 97%, 94.5%, and 95.8% for cemented, uncemented, and hybrid TKAs, respectively. Revision rates were 0.47, 0.74, and 0.52 per 100 component years for cemented, uncemented, and hybrid prostheses, respectively. The revision rate for uncemented prostheses compared with cemented was higher (P < .001). When stratified by age group, there were differences in survival rates between cemented and uncemented groups (P = .001) and hybrid and uncemented groups (P = .038) in patients aged <55 years; between cemented and uncemented groups in those aged 55-64 years (P = .031); and between cemented and hybrid groups in those aged >75 years (P = .004).

CONCLUSION

Uncemented TKAs had similar patient-reported outcomes but higher revision rates and worse survivorship compared with hybrid or fully cemented TKAs.

An optimum prosthesis combination of low-risk total knee arthroplasty options in all five primary categories of design results in a 60% reduction in revision risk: a registry analysis of 482,373 prostheses

PURPOSE

Decades of innovations in total knee arthroplasty (TKA) design have led to large number of possible prosthesis combinations in regards fixation, posterior stability, bearing mobility, bearing surface, and patella resurfacing, each of which can alter the revision risk. The accumulative effect when the lowest risk combination in each design category, or "Optimum Prosthesis Combination" (OPC) is utilized remains unknown. The purpose of this analysis was to first, identify the OPC and second, to compare the revision risk of a cohort who received the OPC to a cohort who received an Alternative Prosthesis Combination (APC).

METHODS

National registry revision risk data for primary TKA for osteoarthritis were obtained from September 1999 to December 2015 for two patient cohorts, those receiving an OPC and those receiving an APC. OPC was defined as TKA with the lowest revision risk option for five primary TKA design categories; fixation, posterior stability, bearing mobility, bearing surface, and patella resurfacing, while APC had one or more higher risk options.

RESULTS

Of the 482,373 included TKA, 42,008 (8.7%) were in the OPC cohort, who received a minimally stabilized, fixed bearing TKA with cross-linked polyethylene with patella resurfacing. Both cohorts had similar demographics. At 10 years, the OPC cohort had a Cumulative Percent Revision of 2.4% (95% CI 2.1, 2.8) compared to 5.5% (95% CI 5.4, 5.6) for the APC cohort. For all patients, revision risk of the APC cohort was higher at all times [151% greater at ≥ 3 years (p < 0.001)]. Loosening/lysis was the most common cause of revision in the ACP cohort (1.1%), while it was the second most common cause in the OPC cohort (0.3%). The increased risk was apparent in all age and gender subgroups, with the highest risk increase seen in males ≥ 65 years.

CONCLUSIONS

Patients receiving the lowest risk prosthesis design combination or Optimum Prosthesis Combination TKA had a 60% lower revision risk, with similar demographics to the Alternative Prosthesis Combination TKA.

LEVEL OF EVIDENCE

III.

Equivalent 2-year stabilization of uncemented tibial component migration despite higher early migration compared with cemented fixation: an RSA study on 360 total knee arthroplasties

Background and purpose - Thresholds of implant migration for predicting long-term successful fixation of tibial components in total knee arthroplasty have not separated cemented and uncemented fixation. We compared implant migration of cemented and uncemented components at 1 year and as the change in migration from 1 to 2 years. Patients and methods - Implant migration of 360 tibial components measured using radiostereometric analysis was compared at 1 year and as the change in migration from 1 to 2 years in 222 cemented components (3 implant designs) and 138 uncemented components (5 implant designs). Results - 1-year maximum total point motion was lower for the cemented tibial components compared with the uncemented components (median = 0.31 mm [0.03-2.98] versus 0.63 mm [0.11-5.19] respectively, p < 0.001, mixed model). The change in migration from 1 to 2 years, however, was equivalent for cemented and uncemented components (mean [SD] 0.06 mm [0.19] and 0.07 mm [0.27] mm respectively, p = 0.6, mixed model). Interpretation - These findings suggest that current thresholds of acceptable migration at 1 year may be better optimized by considering cemented and uncemented tibial components separately as higher early migration of uncemented components was not associated with decreased stability from 1 to 2 years.

The effect of surgeon's preference for hybrid or cemented fixation on the long-term survivorship of total knee replacement

Background and purpose - Recent direct comparative reports suggest that hybrid fixation may have a similar or superior outcome to cemented fixation in total knee replacement (TKR); however, a paucity of long-term data exists. To minimize the confounders of a direct comparison, we performed an instrumental variable analysis examining the revision rate of 2 cohorts of patients based on their surgeon's preference for cemented or hybrid fixation. Methods - Registry data were obtained from 1999 until 2015 for 2 cohorts of patients who received minimally stabilized TKR, defined as those treated by high-volume hybrid fixation preferring surgeons, designated routinely hybrid (RH), and those treated by high-volume cemented fixation preferring surgeons, designated routinely cemented (RC). Results - At 13 years, the cumulative percentage revision of the RC cohort was 4.8% (CI 4.1-5.7) compared with 5.5% (CI 3.5-8.7) for the RH cohort. The revision risk for each cohort was the same for all causes (HR =1.0 (CI (0.84-1.20)), non-infective causes, and for infection. This finding was irrespective of patient age or sex, patella resurfacing, and with non-cross-linked polyethylene (NXLPE). The RH cohort who received cross-linked polyethylene (XLPE) had a lower revision risk than the RC cohort with XLPE (HR =0.57 (0.37-0.88), p = 0.01). Interpretation - The risk of revision for the patients of surgeons who prefer cemented fixation in minimally stabilized TKR is the same as for the patients of surgeons who prefer hybrid fixation, except when used with XLPE, where hybrid fixation has a lower revision risk.

Uncemented vs Cemented Cruciate Retaining Total Knee Arthroplasty in Patients With Body Mass Index Greater Than 30

BACKGROUND

Aseptic loosening of cemented and uncemented tibial components continues to be a source of implant failure after total knee arthroplasty (TKA) in the obese population. There is limited literature reviewing uncemented cruciate retaining (CR) components in the obese population.

METHODS

A clinical and radiographic review was performed on 325 patients who underwent a cemented or uncemented TKA with a CR knee prosthesis and body mass index ≥30 kg/m² between January 2010 and June 2013. Charts were reviewed for the incidence of revision due to aseptic loosening of the tibial baseplate, revision for any reason, incidence of radiolucent lines around the tibial baseplate, range of motion, and patient reported outcomes.

RESULTS

There was no statistically significant difference between groups in survivorship for aseptic loosening of the tibial component (99.4% uncemented, 99.3% cemented, P = .94) and overall survivorship (98.1% uncemented, 98.3% cemented, P = .90). The Lower Extremity Activity Scale and Forgotten Joint Score-12 clinical outcome measures were similar between groups (10.2 ± 3.7 vs 9.7 ± 3.4 and 66.1 ± 28.2 vs 64.9 ± 24.3, P = .33, P = .78, respectively). Postoperative knee flexion was similar between groups (114.6 ± 9.3 vs 114.1 ± 9.3, P = .67).

CONCLUSION

Our study demonstrated similar survivorship of this CR design for aseptic loosening of the tibial baseplate and overall revision rates in obese patients undergoing either an uncemented or cemented TKA. The uncemented and cemented groups had comparable clinical and radiographic short to mid-term outcomes when implanted in good alignment when treating end-stage knee osteoarthritis.