Evolution of tibial fixation in total knee arthroplasty

Bisphosphonate Use in Patients Who Have Osteoporosis Does Not Increase the Risk of Periprosthetic Fracture Following Total Knee Arthroplasty

BACKGROUND

The purpose of this study was to evaluate the effect of preoperative bisphosphonate use in patients who have osteoporosis on the risk of complications following primary total knee arthroplasty (TKA).

METHODS

An administrative claims database was queried for patients who have osteoporosis undergoing primary TKA between 2010 and 2019 with a minimum of 2-year follow-up. Bisphosphonate-naive patients and bisphosphonate users, defined as patients who had a continuous prescription for bisphosphonates for a minimum of 6 months preoperatively, were matched 1:1 based on age, sex, and comorbidity burden. Patients undergoing nonelective TKA on chronic glucocorticoid therapy or receiving any other pharmacologic treatment for osteoporosis were excluded. The final cohort included 21,058 matched pairs of patients. The incidence of postoperative complications was identified via International Classification of Disease coding and compared between matched groups. A subgroup analysis was performed to examine outcomes among patients who underwent cemented and cementless TKA.

RESULTS

There was no difference in the incidence of periprosthetic fracture on univariate (0.7 versus 0.8%, P = 0.068) or multivariate testing (OR [odds ratio]: 1.24, 95% confidence interval [0.99 to 1.56]; P = 0.060). Bisphosphonate users were statistically less likely to undergo all-cause revision TKA at 2 years (OR: 0.84 [0.72 to 0.97]; P = 0.021). Patients who had osteoporosis were found to have an increased risk of periprosthetic fracture when TKA was performed with cementless implants (1.6 versus 0.4%; P = 0.033). However, when treated with bisphosphonates, patients who have osteoporosis demonstrated equivalent fracture rates regardless of implant type (1.3 versus 1.0%; P = 1.000).

CONCLUSIONS

While bisphosphonate use in patients who have osteoporosis did not decrease the risk of periprosthetic fracture, it did significantly lower the incidence of all-cause revision at 2 years, although the difference identified was small. Consideration should be given to performing cemented TKA in patients who have untreated osteoporosis, given the higher rate of periprosthetic fracture when cementless implants were utilized.

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.

Uncemented Total Knee Arthroplasty in the State of Michigan has Higher Rates of Revision Through 5-Year Follow-Up

BACKGROUND

While cemented total knee arthroplasty (TKA) is considered the gold standard, uncemented designs are gaining popularity, especially in young men who are at higher risk of cemented failure. Assessing this growth's impact, the Michigan Arthroplasty Registry Collaborative Quality Initiative analyzed adoption rates of uncemented TKA and the effect of fixation technique on revision rates with the goal of assessing the revision rates and survivorship at five years of cemented versus uncemented TKA to further classify which patients may be more ideal candidates for cementless fixation.

METHODS

The Michigan Arthroplasty Registry Collaborative Quality Initiative data from 2017 to 2022 was analyzed to determine the survivorship of cemented versus uncemented TKAs. Descriptive statistics, demographics, and implant type were collected. Cumulative percent revision (CPR) was calculated based on the fixation method. The primary endpoint was time for the first revision. Kaplan-Meier survival curves were compared. Subanalyses were performed based on age, sex, body mass index, and implant type. Confidence intervals were set to 95%.

RESULTS

The registry query yielded 147,838 TKAs. There were 18,523 (12.5%) uncemented TKAs. Uncemented TKA use increased yearly from 2017 to 2022 in all groups. Uncemented TKA had higher CPR through five years at all time points versus cemented (3.65 versus 3.19%, P < 0.0001). Uncemented TKA performed worse in both men and women (P < 0.01, P < 0.01). Unexpectedly, men < 55 years had higher CPR at all time points for the four most used implants (P < 0.05).

CONCLUSIONS

The use of uncemented TKA has grown in Michigan across all patient subgroups. Uncemented TKAs had an overall higher risk of revision compared to cemented TKAs. The poorer outcomes appeared consistent across sex, age, and implant type. Younger men who are often preferred for uncemented fixation had higher failure rates. This study suggests that surgeons should be mindful of revision rates and patient selection when moving to uncemented TKA.

Floating-embedded stems reduce tibial stress shielding in total knee revision arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is one of the most common orthopaedic procedures and the number of patients which undergo TKA will continue to rise in the coming years. Consecutively, the number of necessary revision surgeries will increase. One of the main reasons for revision surgery is aseptic loosening because of a so-called stress-shielding effect. Typically, revision of a primary TKA is done from a bicondylar surface replacement to a stem-anchored prosthesis, which, due to higher stress-shielding, have a shorter survival time than non-stem-anchored systems. Similar to endoprosthetic treatment in pediatric tumor orthopedics, non-ingrown cementless stems can be used. The study aim was to investigate whether this concept can also be applied to reduce stress-shielding in the tibial metaphysis after revision TKA in adults.

METHODS

Six tibial biomechanical bone with stemmed tibial TKA components were implanted using surface cementing and a floating-embedded stem or classic full cementing. After implantation, axial force was applied in such a way that the same load was generated as during walking. Two high-resolution cameras and illumination spots were used to record changes on the bone surface circumferentially in three regions of interest and from three different views.

RESULTS

With regard to the fixation method, a significant difference could be demonstrated in the metaphyseal and in the middle region around the stem (p < 0.001). At the tip of the stems, the reduction of strain energy density showed a stress shielding reduction for the floating-stemmed models in two of three views (ventromedial p = 0.002, lateral p = 0.398, and dorsal: p = 0.027).

CONCLUSIONS

In revision surgery after TKA, the use of floating-embedded, uncemented stems without bony ingrowth shows significant reduction of metaphyseal stress-shielding within the proximal tibia. This technique could be a viable alternative to prevent early aseptic loosening and should be examined in future in-vivo studies.

Survivorship of Primary NexGen Knee Replacement: Comparing Cementless Trabecular Metal to Other Designs of Tibial Component

The impact of cementless trabecular metal (TM) implants on implant survivorship are not well delineated. This study compares primary total knee arthroplasty (TKA) revision rates of cemented knee replacements with two cementless knee replacement designs-cementless TM and a non-TM cementless design. Data from a national registry queried TKA procedures performed for osteoarthritis from 1999 to 2020. The risk of revision of Zimmer NexGen TKA using cementless TM, cementless non-TM, and cemented non-TM were compared. Analyses included Kaplan-Meier estimates of survivorship and Cox hazard ratios (HR), stratified by age and gender. Cementless TM components had higher risks of revision compared with cementless non-TM implants (HR = 1.49; p ≤ 0.001). Cementless TM implants showed higher risks of revision compared with cemented non-TM prostheses for the first 2 years (HR = 1.75, p < 0.001). Non-TM prostheses posed equal risk of revision for cementless and cemented fixations (HR = 0.95, p = 0.522). Patients aged 55 to 64 years and 65 to 74 years had a higher risk of revision for cementless TM compared with cementless non-TM (HR = 1.40, p = 0.033 and HR = 1.79, p < 0.001, respectively) and cemented non-TM implants (HR = 1.51, p < 0.001 and HR = 1.54, p < 0.001, respectively). The study shows there is an increased risk of revision with TM cementless implants for patients aged 55 to 74 years. These results do not support the use of TM tibial implants for patients of this age group for primary TKA.

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 Versus Cemented Total Knee Arthroplasty of the Same Design: Shorter Operative Times and Minimal Differences in Early Outcomes

Introduction: Modern primary cementless total knee arthroplasty (TKA) is increasingly popular, but there is limited evidence on its benefits, early complications, and failures. Purpose: We sought to evaluate operative time, early survivorship, and outcomes of cementless versus cemented TKA of the same design. Methods: As part of this single-center, multisurgeon, retrospective cohort study, we reviewed 598 primary, unilateral TKAs (170 cementless, 428 cemented) of the same design from 2016 to 2018. The cementless cohort was younger (63 vs 67 years) and had more cruciate-retaining implants (17% vs 12%) compared with the cemented cohort. We compared operative time, length of stay, and complications. Survivorship curves were generated via the Kaplan-Meier method. Results: Patients with cementless TKA (using the Triathlon implant, Stryker) had a 24% reduction in operative time (83 vs 109 minutes) but similar length of stay compared with those with cemented TKA (57 vs 61 hours). Cementless TKA had a higher rate of postoperative manipulation for stiffness compared with cemented TKA (8% vs 3%), but there were notable demographic differences between the cohorts. Despite 2 cases (1%) of early cementless tibial aseptic loosening requiring component revision compared with none in the cemented cohort, there was no difference in revision-free survivorship at 2 years (96% and 98%, respectively). Conclusion: This retrospective cohort study found that cementless TKA had a 24% reduction in operative time compared with cemented TKA and similar short-term survivorship. There was a slightly higher rate of aseptic revision and manipulation in the cementless cohort. Further study is warranted on the long-term durability of cemented and cementless TKAs to determine if cementless fixation proves more durable in the midterm to long term.

Cemented total knee arthroplasty provides greater knee range of motion at 2 years than cementless technique

INTRODUCTION

Optimal fixation method between cemented, cementless, and hybrid techniques for total knee arthroplasty (TKA) is still debated. The purpose of this study is to evaluate the clinical outcomes of patients undergoing cemented versus cementless TKA.

METHODS

We reviewed 168 patients who underwent a primary TKA at a single academic institution between January 2015 and June 2017. Patients were categorized into cemented (n = 80) or cementless (n = 88) groups. Only patients with greater than or equal to 2-year follow-up were included in the study. Multivariate regressions were performed to analyze the relationship between the surgical fixation technique and the clinical outcomes.

RESULTS

There were no differences in demographics or baseline operative characteristics between the two groups. The cemented group had fewer manipulations under anesthesia (MUA) (4 vs. 15, p = 0.01), longer intraoperative tourniquet times (101.30 vs. 93.55 min, p = 0.02), and increased knee range of motion (ROM) at final follow-up (111.48 vs. 103.75°, p = 0.02) compared to the cementless group.

DISCUSSION AND CONCLUSION

Both cemented and cementless component fixation are viable options for (TKA). This study found that patients who underwent a cemented TKA required fewer MUA's and had greater final ROM compared to patients undergoing cementless TKA. Additional research is required regarding cementless and cemented fixation. We believe that the choice of which fixation technique to use ultimately comes down to patient characteristics and surgeon preference.

Patients Undergoing Primary, Cementless TKA had Similar Pain, Opioid Utilization, and Functional Outcomes Compared to Matched Patients With Cemented Fixation

BACKGROUND

Despite renewed interest in cementless fixation of total knee implants, many surgeons have anecdotal concerns about slower recovery and higher early pain scores. We sought to analyze 90-day opioid utilizations, inhospital pain scores, and patient-reported outcome measures (PROMs) in patients undergoing primary cemented versus cementless total knee arthroplasty (TKA).

METHODS

We retrospectively identified a cohort of opioid naïve patients undergoing primary TKA for osteoarthritis. There were 186 patients who had cementless TKAs matched 1:6 with 1,116 who received a cemented TKAs based on age (±6 years), body mass index (BMI) (±5), and sex. We compared inhospital pain scores, 90-day opioid utilizations in morphine milligram equivalents (MMEs), and early postoperative PROMs.

RESULTS

The cemented and cementless cohorts had similar lowest (0.09 versus 0.08), highest (7.36 versus 7.34), and average (3.26 versus 3.27) pain scores using numeric rating scale (P > .05). They received similar inhospital (90 versus 102, P = .176), discharge (315 versus 315, P = .483), and total (687 versus 720, P = .547) MMEs. They had similar average inpatient hourly opioid consumption (2.5 versus 2.5 MMEs/hour, P = .965). Average refills 90 days postoperatively were similar in both cohorts (1.5 versus 1.4 refills, P = .893). Also, preoperative, 6-week, 3-month, delta 6-week, and delta 3-month PROMs scores were similar between cemented and cementless cohorts (P > .05) CONCLUSION: This matched study demonstrated similar in-hospital pain scores and opioid utilization, total MMEs prescribed within 90 days, and PROMs at 6 weeks and 3 months postoperatively between cemented and cementless TKAs.

LEVEL OF EVIDENCE

III, retrospective cohort study.

A Systematic Review and Network Meta-Analysis of the Outcomes of Patients With Total Knee Arthroplasty Using Cemented, Uncemented, or Hybrid Techniques

In this study, we aim to explore the differences among the three types of fixation methods for the components of the knee joint in patients who underwent total knee arthroplasty (TKA). These methods are cemented, uncemented, and hybrid fixation. Cemented fixation means that a special type of grout is used to attach the components to the bone. Uncemented fixation means that the components are designed to fit tightly into the bone and allow new bone growth to secure them. Hybrid fixation means that a combination of cemented and uncemented fixation is used for different components. We searched four online databases to find studies relevant to our research question. We use the R program (R Foundation for Statistical Computing, Vienna, Austria) for network meta-analysis (NMA) to analyze the data from the studies. We calculate the mean difference (MD) and the 95% confidence interval (CI) for each outcome, which are statistical measures of the difference and the uncertainty between methods. We use these measures for continuous outcomes, meaning they can have any value. For dichotomous outcomes, meaning they can only have two values, we use the risk ratio (RR) and the 95% CI, which are statistical measures of the relative risk and the uncertainty between methods. We assess the quality of randomized controlled trials, which are studies that randomly assign participants to different methods, using the Cochrane Risk of Bias Assessment Tool 1, a tool that evaluates the potential biases in the studies. We include 21 studies, and our analysis shows that cemented TKA reveals a statistically significant decrease in pain with hybrid TKA (MD = -2.82). That said, we find no significant differences between uncemented and cemented or hybrid (MD = -0.80 and -2.02, respectively). The results show that there is no significant difference between uncemented TKA and cemented TKA or hybrid technique (RR = 0.87, 95% CI 0.35-2.14; RR = 0.73, 95% CI 0.22-2.39, respectively). Also, we find no significant difference between cemented TKA and hybrid TKA (RR = 0.84, 95% CI 0.24-2.93). Cemented TKA is associated with a lower risk of deep vein thrombosis (DVT) incidence rate. Moreover, it shows a significant decrease in pain compared to hybrid TKA. Future research is needed to compare among the three interventions.

A prospective randomised controlled trial of cemented and uncemented tibial baseplates: functional and radiological outcomes

INTRODUCTION

With the success of uncemented fixation in younger patients undergoing total hip arthroplasty and the growing demand for total knee arthroplasty (TKA) in a younger cohort of patients, there has been an increasing interest in cementless tibial baseplate fixation. We sought to determine whether there was a clear advantage to the use of three different forms of tibial baseplate fixation. The primary outcome of this study was survivorship and secondary outcomes were functional and radiological outcomes, up until 10 years.

MATERIALS AND METHODS

We conducted a randomised controlled trial and recruited 224 patients with 274 knees. Patients underwent TKA by a single surgeon utilising a standard surgical technique. All patients received a cruciate retaining TKA with a cementless femoral component, and were randomised to receive either a cemented tibial component, a pegged porous coated cementless tibial component with screws or a cementless tantalum monoblock tibial component with pegs. Patient reported outcome measures (PROMS), radiological data and survivorship were assessed until 10 years post-operatively.

RESULTS

Pre-operative range of motion, alignment and PROMS were similar between the three groups. The use of cemented, cementless with screws or cementless with pegs fixation options, lead to differences in functional outcomes. There was greater improvement in the Oxford score and Knee Society Score in patients who received a cemented baseplate compared to tantalum and the pegged porous groups. However, radiological and survival outcomes were similar in all three groups. Overall survivorship was 99.6%, with one knee with cementless tibial fixation and screws revised for subsidence at 3 years. There were no cases of venous thromboembolism, periprosthetic fracture or infection.

CONCLUSIONS

Irrespective of tibial fixation method, functional and radiological outcomes remain similar at follow-up at 10 years, with no clear difference in outcome between each group. Each method of fixation also had excellent survivorship over this period and should reassure surgeons that whichever method of fixation they choose, long-term outcomes are likely to be satisfactory.

Cementless Total Knee Arthroplasty is Associated With Early Aseptic Loosening in a Large National Database

BACKGROUND

Despite excellent longevity demonstrated in institutional studies, outcomes after cementless total knee arthroplasty (TKA) on a population level remain unknown. This study compares 2-year outcomes between cemented and cementless TKA using a large national database.

METHODS

A large national database was used to identify 294,485 patients undergoing primary TKA from January 2015 to December 2018. Patients who had osteoporosis or inflammatory arthritis were excluded. Cementless and cemented TKA patients were matched one-to-one based on age, Elixhauser Comorbidity Index, sex, and year yielding matched cohorts of 10,580 patients. Outcomes at 90 days, 1 year, and 2 years postoperatively were compared between groups, and Kaplan-Meier analysis was used to evaluate implant survival rates.

RESULTS

At 1 year postoperatively, cementless TKA was associated with an increased rate of any reoperation (odds ratio [OR] 1.47, 95% confidence interval [CI] 1.12-1.92, P = .005) compared to cemented TKA. At 2 years postoperatively, there was an increased risk of revision for aseptic loosening (OR 2.34, CI 1.47-3.85, P < .001) and any reoperation (OR 1.29, CI 1.04-1.59, P = .019) after cementless TKA. Two-year revision rates for infection, fracture, and patella resurfacing were similar between cohorts.

CONCLUSION

In this large national database, cementless fixation is an independent risk factor for aseptic loosening requiring revision and any reoperation within 2 years after primary TKA.

Early Survivorship of Uncemented Total Knee Arthroplasty Varies by Age and Sex based on Data from the Michigan Arthroplasty Registry Collaborative Quality Initiative

BACKGROUND

Outcome data for newer uncemented total knee arthroplasty designs has been mixed. Registry studies showed worse survivorship, but clinical trials have not demonstrated differences compared to cemented designs. There has been renewed interest in uncemented TKA with modern designs and improved technology. The utilizations of uncemented knees in Michigan, 2-year outcomes, and the effects of age and sex were evaluated.

METHODS

A statewide database from 2017 through 2019 was analyzed for incidence, distribution, and early survivorship of cemented vs. uncemented TKAs. There was 2-year minimum follow-up. Kaplan-Meier survival analysis was used to generate time to first revision cumulative percent revision (CPR) curves. The impacts of age and sex were examined.

RESULTS

Use of uncemented TKAs increased from 7.0 to 11.3%. Uncemented TKAs were more commonly men, younger, heavier, American Society of Anesthesiologists (ASA) Score>2, and opioid users (p<0.05). At 2 years, overall CPR was higher in uncemented (2.44% [2.00, 2.99] versus cemented (1.76% [1.64, 1.89]), particularly in women (uncemented (2.41 [1.87, 3.12]) vs cemented (1.64 [1.50, 1.80]). Revision rates were greater with uncemented women >70 years (1.2% 1 year, 1.02% 2 years) vs <70 years (0.56%, 0.53%), notably uncemented were inferior in both groups (p<0.05). Men, regardless of age, had similar survivorships with both cemented and uncemented designs.

CONCLUSION

The use of an uncemented TKA had an increased risk of early revision compared to cemented. This finding, however, was only apparent in women, especially those >70 years old. Surgeons should consider cement fixation in women >70 years.

The Knee-Fix study: study protocol for a randomised controlled trial evaluating cemented and cementless components in total knee arthroplasty

BACKGROUND

Total knee arthroplasty (TKA) is an effective procedure for patients with a variety of knee conditions. The main cause of aseptic TKA failure is implant loosening, which has been linked to poor cement mantle quality. Cementless components were introduced to offer better longer-term biological fixation through osseointegration; however, early designs led to increased rate of revision due to a lack of initial press-fit and bony ingrowth. Newer highly porous metal designs may alleviate this issue but randomised data of fully uncemented TKA (tibial, femoral, patella) is lacking. The aim of the Knee-Fix study is to investigate the long-term implant survival and patient outcomes of fully uncemented compared with cemented fixation in TKA. Our study hypothesis was that uncemented TKA would be as clinically reliable and durable as the gold-standard cemented TKA.

METHODS

The Knee-Fix study is a two-arm, single-blinded, non-inferiority randomised controlled trial with 160 patients in each arm and follow-up at 6 weeks, 6 months, 12 months, 24 months, 5 years and 10 years. The primary outcome of interest is implant fixation, which will be measured by assessment of postoperative progressive radiolucencies with the Knee Society Total Knee Arthroplasty Roentgenographic Evaluation and Scoring System. Secondary outcome measures are patient-reported outcomes, measured using Oxford Knee Score (OKS), International Knee Society System (IKSS), Forgotten Joint Score-12 (FJS-12), EuroQol (EQ-5D-5L), VAS Pain, Patient Satisfaction Score and Net Promoter Score.

DISCUSSION

While cemented fixation remains the gold standard, a growing proportion of TKA are now implanted cementless. Highly porous metal cementless components for TKA can offer several benefits including potentially improved biological fixation; however, long-term outcomes need further investigation. This prospective study will help discern long-term differences between the two techniques.

TRIAL REGISTRATION

Australian New Zealand Clinical Trials Registry ACTRN12616001624471 . Registered trial name: Knee-Fix study (Cemented vs Uncemented Total Knee Replacement). Registered on 24 November 2016.

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.

Clinical outcomes and survivorship of cementless triathlon total knee arthroplasties: a systematic review

Background

Over the last decade, cementless total knee arthroplasty has demonstrated improved outcomes and survivorship due to advances in technologies of implant design, manufacturing capabilities, and biomaterials. Due to increasing interest in cementless implant design for TKA, our aim was to perform a systematic review of the literature to evaluate the clinical outcomes and revision rates of the Triathlon Total Knee system over the past decade.

Methods

A systematic review of the literature was conducted following PRISMA guidelines for patients who underwent total knee arthroplasty with cementless Triathalon Total Knee System implants. Patients had a minimum of two-year follow-up and data included clinical outcome scores and survivorship data.

Results

Twenty studies were included in the final analysis. The survivability of the Stryker Triathlon TKA due to all causes was 98.7%, with an aseptic survivability of 99.2%. The overall revision incidence per 1,000 person-years was 3.4. Re-revision incidence per 1,000 person-years was 2.2 for infection, and 1.3 for aseptic loosening. The average KSS for pain was 92.2 and the average KSS for function was 82.7.

Conclusions

This systematic review demonstrated excellent clinical outcomes and survivorship at a mean time of 3.8 years. Additional research is necessary to examine the long-term success of the Stryker Triathlon TKA and the use of cementless TKAs in obese and younger populations.

Level of evidence

III.

Cemented Versus Cementless Total Knee Arthroplasty in Obese Patients With Body Mass Index ≥35 kg/m2: A Contemporary Analysis of 812 Patients

BACKGROUND

Cemented total knee arthroplasty (TKA) has been shown to have higher failure rates in obese patients, and cementless TKA may provide more durable fixation. This study compared outcomes and survivorship of obese patients undergoing cemented and cementless TKA of the same modern design.

METHODS

We identified a consecutive series of 406 primary cementless TKA performed in obese patients with body mass index (BMI) ≥35 kg/m² in 2013-2018. Each case was matched 1:1 with 406 cemented TKA based on age, sex, BMI, bearing surface, and year of surgery. Knee Injury and Osteoarthritis Outcome Score for Joint Replacement and Short Form-12 were collected preoperatively, at 6 months and 2 years. Implant survivorship was recorded at mean 4.0 years (range 2.0-7.8).

RESULTS

There was no difference in mean BMI between the cemented (38.6 ± 3.4 kg/m²; range, 35-60) and cementless cohorts (38.7 ± 3.3 kg/m²; range, 35-54; P = .706). Both groups had similar final postoperative scores and improvement in scores at 2 years. Furthermore, a similar percentage met the minimal clinically important difference (Knee Injury and Osteoarthritis Outcome Score for Joint Replacement, 70.0% vs 71.2%, P = .700; Short Form-12 Physical, 74.1% vs 70.4%, P = .240). Both groups demonstrated high 7-year survivorship free from aseptic revision (99.0% vs 99.5%, P = .665).

CONCLUSION

Obese patients with BMI ≥35 kg/m² undergoing cementless and cemented TKA of the same modern design had similar outcomes and survivorship at early to mid-term follow-up. Continued surveillance of this high-risk population is necessary.

Redefining Indications for Modern Cementless Total Knee Arthroplasty: Clinical Outcomes and Survivorship in Patients >75 Years Old

BACKGROUND

Most studies on cementless total knee arthroplasty (TKA) have excluded patients >75 years due to concerns that older patients have poorer bone mineral density and osteogenic activity. This study compared the midterm outcomes and survivorship of cemented and cementless TKA of the same modern design performed in patients >75 years.

METHODS

We identified a consecutive series of 120 primary cementless TKA performed in patients >75 years. Each case was propensity score matched 1:3 with 360 cemented TKA of the same modern design based on age, sex, body mass index, Charlson Comorbidity Index, bilateral procedures, liner type, and year of surgery. Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS-JR) and Short Form-12 (SF-12) were collected preoperatively, at 6 months and 2 years. Implant survivorship was recorded at mean 4.2 years (range, 2.0-7.9).

RESULTS

Mean age was 79.0 ± 3.4 years (range, 75-92) in the cemented cohort and 78.9 ± 3.5 (range, 75-91) in the cementless cohort (P = .769). There was no difference in final postoperative scores or improvement in scores at 2 years. The percentage of patients that met the minimal clinically important difference was also similar (KOOS-JR, 68.9% vs 69.2%, P = .955; SF-12 Physical, 71.7% vs 66.7%, P = .299). Seven-year survivorship free from aseptic revision was 99.4% for cemented knees and 100% for cementless knees (log-rank, P = .453).

CONCLUSION

Patients over 75 years undergoing cementless or cemented TKA of the same modern design had comparable outcomes and survivorship in the midterm. The theoretical risks of cementless fixation in this age group were not realized in this study.

Similar Healthcare Utilization and 1-Year Patient-Reported Outcomes between Cemented and Cementless Primary Total Knee Arthroplasty: A Propensity Score-Matched Analysis

Cementless fixation for total knee arthroplasty (TKA) has gained traction with the advent of newer fixation technologies. This study assessed (1) healthcare utilization (length of stay (LOS), nonhome discharge, 90-day readmission, and 1-year reoperation); (2) 1-year mortality; and (3) 1-year joint-specific and global health-related patient-reported outcome measures (PROMs) among patients who received cementless versus cemented TKA. Patients who underwent cementless and cemented TKA at a single institution (July 2015-August 2018) were prospectively enrolled. A total of 424 cementless and 5,274 cemented TKAs were included. The cementless cohort was propensity score-matched to a group cemented TKAs (1:3-cementless: n = 424; cemented: n = 1,272). Within the matched cohorts, 76.9% (n = 326) cementless and 75.9% (n = 966) cementless TKAs completed 1-year PROMs. Healthcare utilization measures, mortality and the median 1-year change in knee injury and osteoarthritis outcome score (KOOS)-pain, KOOS-physical function short form (PS), KOOS-knee related quality of life (KRQOL), Veteran Rand (VR)-12 mental composite (MCS), and physical composite (PCS) scores were compared. The minimal clinically important difference (MCID) for PROMs was calculated. Cementless TKA exhibited similar rates of median LOS (p = 0.109), nonhome discharge disposition (p = 0.056), all-cause 90-day readmission (p = 0.226), 1-year reoperation (p = 0.597), and 1-year mortality (p = 0.861) when compared with cemented TKA. There was no significant difference in the median 1-year improvement in KOOS-pain (p = 0.370), KOOS-PS (p = 0.417), KOOS-KRQOL (p = 0.101), VR-12-PCS (p = 0.269), and VR-12-MCS (p = 0.191) between the cementless and cemented TKA cohorts. Rates of attaining MCID were similar in both cohorts for assessed PROMs (p > 0.05, each) except KOOS-KRQOL (cementless: n = 313 (96.0%) vs. cemented: n = 895 [92.7%]; p = 0.036). Cementless TKA provides similar healthcare-utilization, mortality, and 1-year PROM improvement versus cemented TKA. Cementless fixation in TKA may provide value through higher MCID improvement in quality of life. Future episode-of-care cost-analyses and longer-term survivorship investigations are warranted.

Radiographic Study in Patients Submitted to Cementless Total Knee Arthroplasties: Minimum Follow-Up of 2 Years

Objective  Radiographic evaluate if there are signs of early loosening of the cementless total knee arthroplasties Amplitude-Score® (Amplitude Surgical SAS, Valence, France), checking with a follow-up time ranging from 2 to 5.75 years (mean of 3.75 years).

Methods  Descriptive longitudinal investigation of observational nature, non-comparative, through a static radiographic study of annual control, of a case series, in a single center, all operated on by the same surgeon (S.M.). All cementless arthroplasties that met the inclusion and exclusion criteria performed from March 2012 to October 2014 were included.

Results  Among the 46 cementless knee arthroplasties evaluated in 40 patients, no radiographic signs of early loosening were verified.

Conclusion  Cementless arthroplasty promotes optimal osteointegration, with no early release, and it is essential that the surgical technique is perfectly respected.

Significant differences in rates of aseptic loosening between two variations of a popular total knee arthroplasty design

Purpose

The NexGen Legacy Posterior Stabilised (LPS) prosthesis (Zimmer Biomet, Warsaw, IN, USA) has augmentable and non-augmentable tibial baseplate options. We have noted an anecdotal increase in the number of cases requiring early revision for aseptic loosening since adopting the non-augmentable option. The purpose of this study was to ascertain our rates of aseptic tibial loosening for the two implant types within five years of implantation and to investigate the causes for any difference observed.

Methods

A database search was performed for all patients who underwent primary total knee arthroplasty (TKA) using the NexGen LPS between 2009 and 2015. Kaplan–Meier curves were plotted to assess for differences in revision rates between cohorts. We collected and compared data on gender, age, body mass index, component alignment and cement mantle quality as these were factors thought to affect the likelihood of aseptic loosening.

Results

Two thousand one hundred seventy-two TKAs were included with five year follow-up. There were 759 augmentable knees of which 14 were revised and 1413 non-augmentable knees of which 48 were revised. The overall revision rate at five years was 1.84% in the augmentable cohort and 3.4% in the non-augmentable cohort. The revision rate for aseptic loosening was 0.26% in the augmentable group and 1.42% in the non-augmentable group (p = 0.0241).

Conclusions

We have identified increased rates of aseptic loosening in non-augmentable components. This highlights the effect that minor implant changes can have on outcomes. We recommend that clinicians remain alert to implant changes and publish their own results when important trends are observed.

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.

Micromotion and Migration of Cementless Tibial Trays Under Functional Loading Conditions

BACKGROUND

The outcome of cementless total knee arthroplasty (TKA) relies on successful bony ingrowth into the implant surfaces. Failures due to aseptic loosening are still reported, especially in younger and more active patients. The objective of this study is to quantify the micromotion of a commercially available design of cementless tibial tray under loading conditions simulating walking and stair descent.

METHOD

A commercially available design of cementless total knee arthroplasty was implanted in 7 cadaveric knees which were preconditioned with 500 cycles of 0°-100° flexion under a vertical load of 1050 N in a custom-built, multiaxial functional activity simulator. This was followed by application of the peak forces and moments occurring during walking and stair descent. During each loading procedure, 3-dimensional motion at the bone-prosthesis interface was measured using digital image correlation.

RESULTS

The tray migrated 101 ± 25 μm on average during preconditioning, which was dominated by rotation in the sagittal plane (92% of total migration), combined with posterior translation (28%) and minimal rotation in the transverse plane (14%). The migration varied 2.7-fold (61-167 μm) between the 6 measurement zones. Stair descent produced significantly higher total micromotion than walking in zone #5 (62 ± 9 vs 51 ± 10 μm, P < .05) and zone #6 (68 ± 17 vs 37 ± 10 μm, P < .05). In addition, during stair descent, the tray exhibited significantly more tilting (anterior zones: 31 ± 17 vs -16 ± 20 μm, P < .05; posterior zones: -60 ± 8 vs -40 ± 7 μm, P < .05) and more anteroposterior displacement in the anterior zones (-25 ± 3 vs -13 ± 2 μm, P < .05) when compared to walking.

CONCLUSION

The relative motion at the bone-prosthesis interface varied substantially around the periphery of the cementless tray. Under the loading conditions evaluated, the tray primarily underwent a rocking motion in the sagittal plane. Compared with walking, stair descent produced significantly more micromotion, especially in the posterior zones.

Midterm Comparison of Tibial Fixation between Posterior Cruciate-Retaining and Substituting Porous Tantalum Total Knee Arthroplasty: Three-Dimensional Computed Tomography Analysis

Porous tantalum tibial component is durable with excellent bone ingrowth, higher knee scores, and long-term survivorship. However, to our knowledge, the effect of posterior cruciate-retaining (CR) and posterior cruciate-substituting (PS) porous tantalum tibial component has not been reported. The aim of the current study was to investigate the prosthetic bone quality between CR porous tantalum tibial component and PS using three-dimensional multi-detector-row computed tomography (3D-MDCT). Porous twenty-two (22) CR total knee arthroplasties and 22 PS received 3D-MDCT at every 6 months up to 5.5 years postoperatively to assess prosthetic bone quality (bone marrow contents/tissue volumes [BMC/TV, mg/cm³]) underneath the pegs of porous tantalum modular tibial component. Clinical outcomes (Knee Society score [KSS], Western Ontario and McMaster Universities (WOMAC), FJS-12, Patella score) were evaluated at a minimum follow-up period of 5.5 years. No statistically significant differences were found in age, gender, body mass index, KSS, and BMC/TV volumes in the proximal tibia between the two groups before total knee arthroplasty (TKA). There were also no significant differences between the CR and PS groups with regard to BMC/TV at every 6 months up to 5.5 years after TKA. At 5.5 years postoperatively, there was no significant difference between the two groups in terms of the KSS, WOMAC, forgotten joint score (FJS-12), and Patella score. The present study revealed that the prosthetic bone quality of the CR porous tantalum tibial component and PS were equivalent at every 6 months up to 5.5 years after TKA. This study reflects level II evidence.

Short-term results of triathlon cementless versus cemented primary total knee arthroplasty

BACKGROUND

Recent studies have demonstrated that aseptic loosening remains a leading cause of failure after total knee arthroplasty (TKA). Cementless fixation is a possible strategy for countering this problem. This study compared short-term survivorship and functional results of patients undergoing primary TKA with cementless versus cemented implants.

METHODS

A multi-center database was utilized to identify 3849 patients undergoing primary TKA between 2012 and 2017 with a minimum two-year follow-up. Patients were divided into cementless (699), and cemented TKA (3150). The outcome of TKA including revision for aseptic or septic reasons, and other outcome variables were compared. Six hundred five patients from the cementless group (case) were matched with 605 patients from the cemented group (controls). Both groups were compared for outcomes and related variables.

RESULTS

Both matched groups were similar in age, race, gender, height, weight, BMI, laterality, femoral component type, follow-up duration, preoperative and postoperative physical and mental health, and functional activities (all p-values>0.05). Although the cementless TKA group had more components in varus alignment (p = 0.015) and were taller (p < 0.001), the aseptic revision rate and time to failure were similar in both groups (p-values = 0.256 and 0.0890 respectively). The rate of revision for infection was also the same in both groups (p = 0.452).

CONCLUSION

Cementless TKA demonstrated an equivalent rate of aseptic and septic failure when compared to cemented TKA in the short-term. Time to aseptic failure was also similar in both groups.

Reduced Aseptic Loosening With Fully Cemented Short-Stemmed Tibial Components in Primary Cemented Total Knee Arthroplasty

BACKGROUND

Recently, the use of short tibial stems in the obese population undergoing total knee arthroplasty (TKA) has been proposed. Thus, we designed a study to assess tibial component survivorship after primary TKA using a single implant both with and without a fully cemented stem extension performed by a single surgeon.

METHODS

A search of our institutional research database was performed. A minimum 2-year follow-up was selected. Cohorts were created according to patient body mass index (BMI; >40 kg/m² and <40 kg/m²) and the presence (stemmed tibia [ST]) or absence (non-stemmed tibia [NST]) of a short tibial stem extension. Kaplan-Meier survival analyses for aseptic loosening and log-rank tests were performed.

RESULTS

A total of 236 patients were identified (ST = 162, NST = 74). Baseline patient characteristics were statistically similar between cohorts with the exception of BMI which was greater in the ST cohort (32.9 kg/m², 30.6 kg/m²; P = .01). Kaplan-Meier survival analysis at 5 years was superior for the BMI < 40 kg/m² cohort (98.9%, 93.1%; P = .045), the ST cohort (100%, 94.5%; P = .006), and the BMI > 40 kg/m² with ST cohort at 4 years (71.4%, 100%; P = .008).

CONCLUSION

Morbid obesity and a short native tibial stem design appear to be associated with aseptic loosening in primary TKA. This appears to be mitigated through the use of an ST. As such, the use of ST may be considered in at-risk patients. Alternatively, implants with longer native stem designs can be employed. Modern short-stemmed tibial components may need to be redesigned.

The Comparative Analysis of Antegrade Versus Retrograde Approach for a Failed Porous Tantalum Rod Removal During Conversion to Total Hip Arthroplasty

Background

The failure of porous tantalum rods applied to patients with osteonecrosis of the femoral head (ONFH) has been increasingly reported during the last few years. Very few studies have reported methods for implant removal. This study aimed at comparing 2 procedures used for the removal of a failed tantalum rod during conversion to total hip arthroplasty (THA).

Material/Methods

A total of 65 patients (65 hips), who underwent THA after failed implantation of a tantalum rod between June 2007 and December 2016, were retrospectively evaluated. These patients were classified into 2 groups depending on whether the antegrade approach (removal of the tantalum rod from the tip to the butt at the lateral femoral cortex, n=27) or retrograde approach (removal of the tantalum rod from the butt at the lateral femoral cortex to the proximal tip, n=38) was used for rod extraction. These 2 groups were compared for incision length, operation time, blood loss, fracture, tantalum debris, Harris hip scores, and the presence of osteolysis and/or radiolucency.

Results

These 2 groups did not present any significant differences in terms of Harris hip score and incision length. However, the operation time (P=0.000), blood loss (P=0.000), amount of tantalum debris (P=0.000), and presence of radiolucency (P=0.046) were greater for the retrograde approach than for the antegrade approach.

Conclusions

The risk of conversion to THA following failed tantalum rod implantation is high. In such cases, the antegrade procedure was found to be a simple and efficient method for removing the trabecular metal rod with the use of a trephine.

Cemented versus uncemented total knee arthroplasty in younger patients: A protocol of retrospective cohort trial

BACKGROUND

Recently, controversy still exists regarding the clinical effects of cemented or cementless technique in young patients in total knee arthroplasty (TKA). In this context, the present study aimed to determine the functional outcomes and clinical reliability of cementless components versus those of conventional cemented components for young patients in primary TKA.

METHODS

A retrospective review of primary TKAs performed with cementless or cemented fixation between May 2010 and February 2019 was conducted with Institutional Review Board approval. All cases were performed by a single surgeon. Institutional review board approval was obtained prior to conducting chart review and analysis. The primary outcome compared between the 2 fixation groups was the rate of postoperative complications and revision related to TKA, occurring at any point in follow-up. Secondary outcome measures included surgical time, Oxford Knee Score, range of motion, and radiographic outcomes such as progressive radiolucent lines, osteolysis, or component migration.

RESULTS

We were able to directly compare the outcomes of cemented versus cementless techniques and might reveal a better technique in TKA.

TRIAL REGISTRATION

This study protocol was registered in Research Registry (researchregistry5459).

Titanium Porous Coating Using 3D Direct Energy Deposition (DED) Printing for Cementless TKA Implants: Does It Induce Chronic Inflammation?

Because of the recent technological advances, the cementless total knee arthroplasty (TKA) implant showed satisfactory implant survival rate. Newly developed 3D printing direct energy deposition (DED) has superior resistance to abrasion as compared to traditional methods. However, there is still concern about the mechanical stability and the risk of osteolysis by the titanium (Ti) nanoparticles. Therefore, in this work, we investigated whether DED Ti-coated cobalt-chrome (CoCr) alloys induce chronic inflammation reactions through in vitro and in vivo models. We studied three types of implant surfaces (smooth, sand-blasted, and DED Ti-coated) to compare their inflammatory reaction. We conducted the in vitro effect of specimens using the cell counting kit-8 (CCK-8) assay and an inflammatory cytokine assay. Subsequently, in vivo analysis of the immune profiling, cytokine assay, and histomorphometric evaluation using C57BL/6 mice were performed. There were no significant differences in the CCK-8 assay, the cytokine assay, and the immune profiling assay. Moreover, there were no difference for semi-quantitative histomorphometry analysis at 4 and 8 weeks among the sham, smooth, and DED Ti-coated samples. These results suggest that DED Ti-coated printing technique do not induce chronic inflammation both in vitro and in vivo. It has biocompatibility for being used as a surface coating of TKA implant.

The effect of fixation type on the survivorship of contemporary total knee arthroplasty in patients younger than 65 years of age: a register-based study of 115,177 knees in the Nordic Arthroplasty Register Association (NARA) 2000-2016

Background and purpose - Cemented fixation is regarded as the gold standard in total knee arthroplasty (TKA). Among working-age patients, there has been controversy regarding the optimal fixation method in TKA. To address this issue, we conducted a register-based study to assess the survivorship of cemented, uncemented, hybrid, and inverse hybrid TKAs in patients aged < 65 years.Patients and methods - We used the Nordic Arthroplasty Register Association data of 115,177 unconstrained TKAs performed for patients aged < 65 years with primary knee osteoarthritis over 2000-2016. Kaplan-Meier (KM) survival analysis with 95% confidence intervals (CI) and Cox multiple-regression model with adjustment for age, sex, and nation were used to compare fixation methods in relation to revision for any reason.Results - The 10-year KM survivorship of cemented TKAs was 93.6% (95% CI 93.4-93.8), uncemented 91.2% (CI 90.1-92.2), hybrid 93.0% (Cl 92.2-93.8), and inverse hybrid 96.0% (CI 94.1-98.1). In the Cox model, hybrid TKA showed decreased risk of revision after 6 years' follow-up compared with the reference group (cemented) (hazard ratio [HR] 0.5 [CI 0.4-0.8]), while uncemented TKAs showed increased risk of revision both < 1 year (HR 1.4 [1.1-1.7]) and > 6 years' (HR 1.3 [1.0-1.7]) follow-up compared to the reference.Interpretation - Both cemented and hybrid TKAs had 10-year survival rates exceeding 92->93% in patients aged < 65 years. Cemented TKA, however, was used in the vast majority (89%) of the operations in the current study. As it performs reliably in the hands of many, it still deserves the status of gold standard for TKA in working-age patients.

Early Results of a Modern Uncemented Total Knee Arthroplasty System

Historically, cementless total knees were associated with early failure, which made cemented total knee arthroplasty the gold standard. Manufacturers have introduced newer uncemented technologies that provide good initial stability and use highly porous substrates for bony in-growth. The authors hypothesized that the implants would have equivalent 90-day clinical and economic outcomes. Prospectively collected data on 252 uncemented knees in the Michigan Arthroplasty Registry Collaborative Quality Initiative database were reviewed. Ninety-day outcomes, demographics, length of stay, complications, emergency department visits, readmissions, and financial data were compared with those of an age-matched group of cemented knees. Uncemented knees had shorter length of stay (1.58 vs 1.87 days; P<.01), were more frequently discharged home (90.48% vs 68.75%; P<.0001), and used less home care (6.35% vs 19.14%; P<.0001) or extended care facilities (2.78% vs 11.72%; P=.0001). More uncemented knees had "no complications." Moreover, there were no re-operations in uncemented knees, compared with 19 reoperations in cemented knees. Uncemented knees were better than age-matched counterparts for Knee injury and Osteoarthritis Outcome Score (63.69 vs 47.10, n=85 and n=43, P<.0001) and Patient-Reported Outcomes Measurement Information System (PROMIS) T-Physical and T-Mental scores (44.12 vs 39.45, P<.0001; 51.84 vs 47.82, P=.0018). Cemented cases were more expensive overall, and surgical ($6806.43 vs $5710.78; P<.01) and total hospital ($8347.65 vs $7016.11; P<.01) costs were higher. The 90-day readmission and hospital outpatient costs were not significantly different between designs. Uncemented total knee arthroplasty, when using modern technologies, is successful and economically viable for an at-risk bundle. The results of this study should alleviate fears of increased cost, early failure, complications, or poor outcomes with the use of a modern uncemented total knee arthroplasty. [Orthopedics. 2019; 42(6):355-360.].

[Predictors for persistent pain and dissatisfaction after total knee arthroplasty]

BACKGROUND

A substantial number of patients patients suffer from persistent pain or are unsatisfied after total knee arthroplasty (TKA).

OBJECTIVES

This work aims to present the frequency of postoperative persistent pain and/or dissatisfaction as well as known causes and predictors.

MATERIALS AND METHODS

The current literature is studied regarding the subject and is reviewed narratively.

RESULTS

Most postoperative problems did not arise from operation details, but from patient-related criteria, a lack of patient education and selection. The satisfaction correlates most strongly with the reduction of preoperative pain.

CONCLUSION

For a successful TKA, care should be taken that the following aspects are met preoperatively: clinically and radiologically advanced osteoarthritis, a patient age preferably older than 60 years, sufficient psychosocial resources to cope with postoperative stress, no opioid medication and realistic expectations after TKA. Postoperatively, patients with persistent pain or dissatisfaction should be checked for any prosthesis-related problems. If no prosthesis-related problems could be detected, the patients should be referred for interdisciplinary therapies.

Cemented Versus Cementless Total Knee Arthroplasty of the Same Modern Design: A Prospective, Randomized Trial

BACKGROUND

Highly porous surfaces promoting biologic fixation have renewed interest in cementless total knee arthroplasty (TKA), but the potential for failed biologic fixation remains. The purpose of this study was to compare the clinical outcomes of cemented and cementless versions of the same TKA design at an average of 2 years postoperatively.

METHODS

This was an institutional review board-approved, prospective, randomized controlled trial of patients from 18 to 75 years of age who were undergoing a primary TKA. Patients with inflammatory arthritis, a body mass index (BMI) of >40 kg/m, infection, a neuromuscular disorder, or grossly osteoporotic bone or bone defects were excluded. Patients were randomized to receive a cemented or cementless cruciate-retaining TKA of the same design. The cementless implant has highly porous fixation surfaces. Oxford Knee, Knee Society, and Forgotten Joint Scores were collected. Patients were asked to rate the knee with the TKA as a percentage of normal. Power analysis indicated that 130 patients were necessary to demonstrate a 5-point difference in the Oxford Knee Score at 90% power.

RESULTS

One hundred and forty-seven patients were enrolled, and 141 (96%) of them were analyzed at an average of 2 years postoperatively. There was no difference in age, sex, BMI, American Society of Anesthesiologists (ASA) score, or duration of follow-up (p = 0.1 to 0.9). There was also no difference in the change in the hemoglobin level from the preoperative measurement to postoperative day 1 between the 2 cohorts (mean and standard deviation, -2.6 ± 1.4 g/dL compared with -2.5 ± 0.9 g/dL, p = 0.5), but the total operative time was decreased in the cementless cohort (82.1 ± 16.6 compared with 93.7 ± 16.7 minutes, p = 0.001). There were no differences in any clinical outcome measure at 4 to 6 weeks, 1 year, or an average of 2 years postoperatively (p = 0.1 to 0.9) between the cemented and cementless cohorts. There was no radiographic evidence of component subsidence or loosening in either cohort.

CONCLUSIONS

This study demonstrated that a recently introduced cementless TKA had results, both perioperatively and at an average of 2 years postoperatively, that were equivalent to those of its cemented predecessor, without any aseptic failures of either implant. Thus, this study justifies continued surveillance of this device to elucidate both its survivorship and if it can provide any long-term benefits.

LEVEL OF EVIDENCE

Therapeutic Level I. See Instructions for Authors for a complete description of levels of evidence.

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

BACKGROUND

The optimal mode of fixation in total knee arthroplasty is a continuing subject of debate.

METHODS

Previously, we reported 2-year results for this prospective, randomized trial. Knee Society Scores, Oxford scores, and pain visual analog scales were collected pre-operatively and post-operatively. Minimum 5-year follow-up has been obtained with radiographic analysis for 85 patients.

RESULTS

Mean Knee Society Scores and Oxford scores and patient-reported outcomes were similar in both groups. Each group had 1 additional revision, but neither was related to implant fixation. Survivorship with revision as an endpoint was equivalent (95.9% and 95.3%, P = .98). There was no significant difference in radiolucencies observed between groups (P = .10), all were non-progressive.

CONCLUSION

Cementless and cemented total knee arthroplasty had equivalent patient-reported outcomes and survivorship at midterm follow-up. Updates are planned at 10 and 15-year intervals to observe long-term modes of failure between these 2 methods of fixation.

Evaluation of a 3D-printed total knee arthroplasty using radiostereometric analysis

Aims

Our intention was to investigate if the highly porous biological fixation surfaces of a new 3D-printed total knee arthroplasty (TKA) achieved adequate fixation of the tibial and patellar components to the underlying bone.

Patients and Methods

A total of 29 patients undergoing primary TKA consented to participate in this prospective cohort study. All patients received a highly porous tibial baseplate and metal-backed patella. Patient-reported outcomes measures were recorded and implant migration was assessed using radiostereometric analysis.

Results

Patient function significantly improved by three months postoperatively (p < 0.001). Mean difference in maximum total point motion between 12 and 24 months was 0.021 mm (-0.265 to 0.572) for the tibial implant and 0.089 mm (-0.337 to 0.758) for the patellar implant. The rate of tibial and patellar migration was largest over the first six postoperative weeks, with no changes in mean tibia migration occurring after six months, and no changes in mean patellar migration occurring after six weeks. One patellar component showed a rapid rate of migration between 12 and 24 months.

Conclusion

Biological fixation appears to occur reliably on the highly porous implant surface of the tibial baseplate and metal-backed patellar component. Rapid migration after 12 months was measured for one patellar component. Further investigation is required to assess the long-term stability of the 3D-printed components and to determine if the high-migrating components achieve fixation. Cite this article: Bone Joint J 2019;101-B(7 Supple C):40–47

A 9-Year Outcome Study Comparing Cancellous Titanium-Coated Cementless to Cemented Tibial Components of a Single Knee Arthroplasty Design

BACKGROUND

The cemented Advance Medial-Pivot total knee arthroplasty (TKA) was designed to reflect contemporary knee kinematics data and has shown satisfactory long-term outcomes.

METHODS

We retrospectively evaluated prospectively collected data from 2 groups of patients. Group A consisted of 54 patients (54 TKAs), 18 men and 36 women, and mean age at surgery was 63.2 ± 5.2 years; group B consisted of 54 patients (54 TKAs), 17 men and 37 women, and mean age at surgery was 63.8 ± 5.1 years. Patients of both groups were matched for age, gender, side, body mass index, and length of follow-up. The cementless components of this design were implanted in group A and the cemented in group B. Implant failure, complication rates, clinical (both subjective and objective) and radiological outcomes were assessed in all patients of both groups.

RESULTS

All patients of both groups were available for final follow-up evaluation at a mean of 8.6 ± 0.4 years. Survival analysis at 9 years showed a cumulative success rate of 100% in both groups with all end points. In neither group were implant-related, surgeon-related, or patient-related failures observed. When both groups were compared, in all time intervals, no differences were recorded on Knee Society system, Western Ontario and McMaster University Osteoarthritis Index, Short Form-12, and Oxford Knee Scores. On radiological examination, for both groups, all parameters evaluated were satisfactory.

CONCLUSION

This study presents satisfactory midterm clinical and radiological outcomes with the use of both versions of this design. Moreover, no implant-related failures were observed with the use of cancellous titanium-coated tibial implants.

A prospective evaluation of a largely cementless total knee arthroplasty cohort without patellar resurfacing: 10-year outcomes and survivorship

BACKGROUND

The theoretical benefits of a mobile bearing design in Total Knee Arthroplasty (TKA) include increased articular surface conformity with a reduction in both polyethylene wear and implant interface shear. However, to date these theoretical advantages have not been translated into published evidence of superior survivorship. This paper presents the results of a prospective, non-comparative study evaluating the performance of the mobile bearing Low Contact Stress LCS Complete Rotating Platform TKA in a largely cementless cohort without patellar resurfacing.

METHODS

237 consecutive patients (240 knees) undergoing primary TKA were prospectively recruited. All received the LCS Complete Rotating Platform TKA (DePuy International, Leeds, UK). Clinical and radiographic assessments were performed at 3, 12, 60 and 120 months post-operatively. Radiographic evaluation was performed by an independent external surgeon.

RESULTS

The mean age was 70.3 years. 77.5% of cases were cementless. Radiographic assessment suggested excellent femoral component fixation. 22 tibial radiolucent lines (RLLs) > 1 mm were observed in 12 knees. No RLLs were progressive. There have been two revisions; one for late infection and one for aseptic loosening. No patients underwent secondary patellar resurfacing. The cumulative implant survivorship, using component revision for any reason as the endpoint, was 98.9% (95% CI, 95.6 to 99.7%) at 10 years.

CONCLUSIONS

The excellent survivorship at a minimum 10-year follow-up supports the use of uncemented porous coated fixation without patellar resurfacing with the non-posterior stabilized LCS Complete Rotating Platform TKA.

Does a simple syringe applicator enhance bone cement set up time in knee arthroplasty?

Background

The time required for polymethylmethacrylate (PMMA) cement curing or hardening can be modified by a number of variables including the mixing technique, and the temperature and pressure at which the process is taking place. Therefore, the purpose of this study was to evaluate two different methods of PMMA application in terms of set up time. Specifically, we (I) compared the PMMA set up time of cement that remained in the mixing bowl to cement that was placed in a syringe and (II) extrapolated the associated annual cost difference on the national and individual surgeon levels.

Methods

The cement set up time was measured for a total of 146 consecutive patients who underwent either unicompartmental knee arthroplasty (n=136) or patellofemoral arthroplasty (n=10) between January 2016 and April 2017. One pack of PMMA powder and monomer were mixed, placed in a 300 mL small plastic bowl, and mixed with a tongue depressor. Then, 50 mL of the mixed PMMA was placed in a sterile 60 mL syringe with the tip cut to a 6-mm opening, and the syringe was used to apply the cement to the bone and the prosthesis surface. The remaining unused cement in the syringe (syringe group) and the remaining unused cement in the plastic bowl (bowl group) were removed and formed into a two separate 2 cm diameter cubes that were allowed to cure at room temperature on a sterile set of osteotomes. The two cubes of cement were timed for complete PMMA curing. A two-tailed student's t-test was used to compare the curing time for the two groups. Annual cost differences were calculated on the national and individual surgeon level. The total number of daily cases performed and the operative time savings using the syringe applicator was used to find daily and annual cost savings.

Results

The mean time for the cement to set up in the bowl group was 16.8±2.1 minutes, and the mean time for cement set up in the syringe group was 15.1±1.7 minutes. Compared to the bowl group cement set up time, the syringe group set up time was significantly lower (P<0.0001). An estimated 350,000 cemented knee arthroplasties are performed each year in the United States. With 1.7 minutes saved per case, 595,000 operating room minutes per year could be saved, resulting in a nearly $71,000,000 national and $110,000 individual surgeon annual cost savings.

Conclusions

The results of the present study demonstrated that the utilization of a simple, inexpensive syringe applicator enhanced the cement set up time by over one and a half minutes. This may be a result of the pressure differences in the syringe applicator. In addition to the control of and precision of where the cement is placed, the syringe applicator could provide an important potential time advantage to the arthroplasty surgeon.

Perioperative and Early Postoperative Comparison of a Modern Cemented and Cementless Total Knee Arthroplasty of the Same Design

BACKGROUND

Cementless total knee arthroplasty (TKA) designs that incorporate a highly porous, titanium surface have the potential to achieve biologic fixation and improve component survivorship. This study's purpose was to compare perioperative and early postoperative outcomes of a cemented vs cementless TKA of the same design.

METHODS

This was a retrospective review of a consecutive series of TKAs performed at a single institution using a cemented or cementless TKA of the same design (Triathlon, Stryker Inc, Mahwah, NJ). All patients with a minimum of 1-year clinical and radiographic follow-up were reviewed, with 1:1 matching performed for age, gender, body mass index, and preoperative Oxford Knee Score. Chi-square or independent student t tests were used for statistical analyses.

RESULTS

Overall, 62 cemented and 66 cementless TKAs were reviewed, with secondary analyses performed after 1:1 matching of 38 patients in each cohort. In both overall and secondary 1:1 matching analyses, there was no difference in baseline demographics (P = .6-.9). Total operative times were decreased in the cementless cohort (P = .03), but there was no difference in the estimated blood loss or change in hemoglobin levels (P = .2-.7). At a mean of 1.4 ± .5 years postoperatively, patients in both cohorts demonstrated similar improvements in Oxford Knee Scores and satisfaction scores (P = .2-.8), with no patients requiring a revision surgical procedure.

CONCLUSION

A recently introduced cementless TKA design demonstrates excellent perioperative and early postoperative results without failures. Continued surveillance is necessary to elucidate the survivorship and potential long-term benefits of this cementless design.

Teriparatide Treatment Improved Loosening of Cementless Total Knee Arthroplasty: A Case Report

INTRODUCTION

Along with the increase of osteoporotic patients in an aging society, complications in surgeries associated with osteoporosis are also increasing. In cementless total knee arthroplasty (TKA), poor primary stability and subsequent initial loosening of the implant may be seen.

CASE REPORT

The patient, a 75-year-old Asian woman with a history of osteoporosis, underwent cementless TKA. Knee radiography at 5 weeks postoperatively showed radiolucent lines outlined beneath the tibial tray and around the stem. The tibial component was considered unstable due to loosening. A 56.5 µg weekly dose of teriparatide (rh [1-34] parathyroid hormone) was administered. After 2 months of treatment, knee pain and knee swelling had disappeared. Tomosynthesis taken after 6 months of treatment confirmed complete ingrowth of the component to the bone.

CONCLUSION

This case showed that a weekly teriparatide administration of 56.5 µg improved initial loosening of the tibial implant in cementless TKA. Administration of teriparatide in cases of the osteoporotic patient who has loosening in cementless TKA may be a useful adjuvant to achieve bone ingrowth again.

Cementless Porous Tantalum Monoblock Tibia vs Cemented Modular Tibia in Primary Total Knee Arthroplasty: A Meta-Analysis

BACKGROUND

With the introduction of new fixation systems and designs, there has been a recent reemergence of interest in cementless fixation of the tibial component in total knee arthroplasty. However, little is known regarding the clinical features and survivorship of the cementless porous tantalum monoblock tibial component compared to the conventional cemented modular tibial component.

METHODS

We conducted a literature search of multiple databases for comparative studies published before June 2015 that investigated the outcomes of cementless porous tantalum monoblock tibia vs conventional cemented modular tibia. A pooled analysis was performed. The outcomes of interest were postoperative functional score, range of motion, Western Ontario and McMaster University Osteoarthritis Index, total complications, reoperation, radiolucent lines, loosening of the tibial component, and length of operation.

RESULTS

Six studies involving 977 patients were eligible for the meta-analysis. The use of a cementless porous tantalum monoblock tibial component may associate with a slightly higher functional score, fewer radiolucent lines, and shorter operation. No significant difference was seen in regard to the range of motion, Western Ontario and McMaster University Osteoarthritis Index, total complications, reoperation, and loosening of the component between the 2 groups.

CONCLUSION

However, due to variation among the included studies, the use of cementless porous tantalum monoblock tibia seems to achieve no substantial superiority over that of the conventional cemented modular tibia at 5-year follow-up. Data concerning the long-term prognosis of this novel implant should continue to be collected and analyzed.

Progranulin suppresses titanium particle induced inflammatory osteolysis by targeting TNFα signaling

Aseptic loosening is a major complication of prosthetic joint surgery, characterized by chronic inflammation, pain, and osteolysis surrounding the bone-implant interface. Progranulin (PGRN) is known to have anti-inflammatory action by binding to Tumor Necrosis Factor (TNF) receptors and antagonizing TNFα. Here we report that titanium particles significantly induced PGRN expression in RAW264.7 cells and also in a mouse air-pouch model of inflammation. PGRN-deficiency enhanced, whereas administration of recombinant PGRN effectively inhibited, titanium particle-induced inflammation in an air pouch model. In addition, PGRN also significantly inhibited titanium particle-induced osteoclastogenesis and calvarial osteolysis in vitro, ex vivo and in vivo. Mechanistic studies demonstrated that the inhibition of PGRN on titanium particle induced-inflammation is primarily via neutralizing the titanium particle-activated TNFα/NF-κB signaling pathway and this is evidenced by the suppression of particle-induced IκB phosphorylation, NF-κB p65 nuclear translocation, and activity of the NF-κB-specific reporter gene. Collectively, these findings not only demonstrate that PGRN plays an important role in inhibiting titanium particle-induced inflammation, but also provide a potential therapeutic agent for the prevention of wear debris-induced inflammation and osteolysis.

To Cement or Not? Two-Year Results of a Prospective, Randomized Study Comparing Cemented Vs. Cementless Total Knee Arthroplasty (TKA)

The optimal mode of fixation in total knee arthroplasty (TKA) is a subject of debate. We enrolled 100 TKA patients randomized to cemented or cementless fixation. Knee Society Scores (KSS), Oxford scores and pain visual analog scales (VAS) were collected pre-operatively and post-operatively. Two-year follow-up was obtained for 93 patients. The mean VAS trended higher for the cementless group at 4 months (P=0.06). At 2 years, the KSS functional scores, Oxford scores, and self-reported questions for satisfaction, less pain and better function were similar but the cemented group had higher KSS clinical scores (96.4 vs. 92.3, P=0.03). More radiolucencies were seen in cementless knees (P<0.001). The cementless group had one revision for instability and one cemented knee was revised for infection. Cementless TKA showed equivalent survivorship (revision for any reason as the endpoint) compared to cemented TKA at this early follow-up. Close monitoring of radiolucencies is important with continued follow-up.

The Mark Coventry Award: Trabecular metal tibial components were durable and reliable in primary total knee arthroplasty: a randomized clinical trial

BACKGROUND

Although highly porous metals have demonstrated excellent bone ingrowth properties and so are an intriguing option for fixation in total knee arthroplasty (TKA), some surgeons are skeptical about the durability of uncemented tibial fixation and the potential for soft tissues to adhere to these porous metals and perhaps cause knee stiffness or pain.

QUESTIONS/PURPOSES

The purpose of this study was to compare, in the context of a randomized clinical trial, a highly porous metal tibia compared with a traditional modular cemented tibia in terms of survivorship, Knee Society scores, range of motion (ROM), and complications.

METHODS

From 2003 to 2006, 397 patients (age 67.8 ± 8.7 years; 54% female) were randomized to three groups: (1) traditional modular cemented tibia; (2) cemented highly porous metal tibia; and (3) uncemented highly porous metal tibia. The same posterior-stabilized femoral component and patella component were cemented in every case. Stratified randomization was done for surgeon, patient's age, sex, and body mass index. Survivorship at 5 years was compared between the groups, as were Knee Society scores, ROM, and complications. Radiographic assessment included alignment, radiolucency, and implant migration/loosening. Patients were followed until death, revision, or for a minimum of 2 years (mean, 5 years; range, 2-9 years). Four patients were lost to followup before 2 years.

RESULTS

Highly porous metal tibias (both uncemented and cemented) were no different from traditional cemented modular tibial modular components in terms of survivorship at 5 years using a intention-to-treat analysis (96.8% [1]; 97.6% [2]; 96.7% [3]; p = 0.59). A per-protocol analysis revealed that no highly porous metal tibia was revised for aseptic loosening. Highly porous metal tibias performed comparably to traditional cemented modular tibias in terms of Knee Society scores, ROM, and the frequency of complications.

CONCLUSIONS

At 5 years this randomized clinical trial demonstrated that highly porous metal tibias provided comparably durable fixation and reliable pain relief and restoration of function when compared with a traditional cemented modular tibia in TKA.

LEVEL OF EVIDENCE

Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

Cemented versus cementless fixation of a tibial component in LCS mobile-bearing total knee arthroplasty performed by a single surgeon

Although cemented tibial fixation of total knee arthroplasty accepted as the gold standard, cementless fixation as a means to supplement disadvantages of cemented fixation continues to be of interest to clinicians. One hundred sixty-eight consecutive knees undergoing primary knee arthroplasty for osteoarthritis were randomly assigned to receive either a cemented (86 knees) or cementless (82 knees) fixation of tibial component. We report the outcomes at 8 to 11years (mean, 9.5). The mean KSS, the HSS score, the mean WOMAC, the mean ranges of knee movement and radiological results were similar in both groups. No osteolysis was identified in either group. The rate of survival of the femoral and tibial components was 100% in both groups at final follow-up.

Effect of tibial tray design on cement morphology in total knee arthroplasty

Background

Improvements to enforce primary fixation in cemented total knee arthroplasty have been suggested to be a key issue for long-term survival. In this context, it has been questioned whether specific implant design features influence bone cement morphology and hence primary interface strength. The purpose of this study was to investigate in vitro the influence of cement pockets on the tibial tray on cement penetration in the tibia.

Methods

Eight paired cadaveric, human tibiae were available for investigation. One side of a pair was implanted with a fixed bearing tibial tray (FB) featuring cement pockets on the undersurface, while in the other side, a mobile bearing platform (MB) without cement pockets was used. Specimens underwent computed tomography analysis of the cement morphology as well as BMD assessment.

Results

While bone cement layer between implant and bone surface was thicker in the FB group (p = 0.032), bone cement penetration was not influenced by implant design (p = 0.529).

Conclusions

The present study suggests that cement pockets do not alter or enforce bone cement penetration under the tibial tray in an in vitro scenario.

Physical and biological characterization of ferromagnetic fiber networks: effect of fibrin deposition on short-term in vitro responses of human osteoblasts

Ferromagnetic fiber networks have the potential to deform in vivo imparting therapeutic levels of strain on in-growing periprosthetic bone tissue. 444 Ferritic stainless steel provides a suitable material for this application due to its ability to support cultures of human osteoblasts (HObs) without eliciting undue inflammatory responses from monocytes in vitro. In the present article, a 444 fiber network, containing 17 vol% fibers, has been investigated. The network architecture was obtained by applying a skeletonization algorithm to three-dimensional tomographic reconstructions of the fiber networks. Elastic properties were measured using low-frequency vibration testing, providing globally averaged properties as opposed to mechanical methods that yield only local properties. The optimal region for transduction of strain to cells lies between the ferromagnetic fibers. However, cell attachment, at early time points, occurs primarily on fiber surfaces. Deposition of fibrin, a fibrous protein involved in acute inflammatory responses, can facilitate cell attachment within this optimal region at early time points. The current work compared physiological (3 and 5 g·L(-1)) and supraphysiological fibrinogen concentrations (10 g·L(-1)), using static in vitro seeding of HObs, to determine the effect of fibrin deposition on cell responses during the first week of cell culture. Early cell attachment within the interfiber spaces was observed in all fibrin-containing samples, supported by fibrin nanofibers. Fibrin deposition influenced the seeding, metabolic activity, and early stage differentiation of HObs cultured in the fibrin-containing fiber networks in a concentration-dependant manner. While initial cell attachment for networks with fibrin deposited from low physiological concentrations was similar to control samples without fibrin deposition, significantly higher HObs attached onto high physiological and supraphysiological concentrations. Despite higher cell numbers with supraphysiological concentrations, cell metabolic activities were similar for all fibrinogen concentrations. Further, cells cultured on supraphysiological concentrations exhibited lower cell differentiation as measured by alkaline phosphatase activity at early time points. Overall, the current study suggests that physiological fibrinogen concentrations would be more suitable than supraphysiological concentrations for supporting early cell activity in porous implant coatings.

Current concepts in knee replacement: features and imaging assessment

OBJECTIVE

This article reviews current concepts of knee replacement. Features of traditional and new prosthetic designs, materials, and surgical techniques are discussed. Normal and abnormal postoperative imaging findings are illustrated. Complications are reviewed and related to the current understanding about how and why these failures occur.

CONCLUSION

It is well known that after knee replacement, patients with complications may be asymptomatic, and, for this reason, assessment of postoperative imaging is important. The foundation of radiologic interpretation of knee replacement is knowledge of the physiologic purpose, orthopedic trends, imaging findings, and complications.

Cementless and cemented total knee arthroplasty in patients younger than fifty five years. Which is better?

PURPOSE

The purpose of this prospective, randomised study was to evaluate long-term clinical results, radiographic findings, complications and revision and survivorship rates in patients <55 years at a minimum of 16 years after undergoing bilateral, sequential, simultaneous, cemented and cementless total knee arthroplasties (TKAs) in the same patients.

METHODS

Bilateral, sequential, simultaneous TKAs were performed in 80 patients (160 knees). There were 63 women and 17 men with a mean age of 54.3 years (range 49-55), who received a cementless prosthesis in one knee and a cemented prosthesis in the other. The mean follow-up was 16.6 years (range 16-17).

RESULTS

At final review, the mean Knee Society (KS) knee scores (95.8 versus 96.9), Western Ontario and McMaster Universities (WOMAC) osteoarthritis (OA) index (25.4 versus 25.9), range of motion (ROM) (125° versus 128°), patient satisfaction (8.1 versus 8.3) and radiological results were similar in both groups. Femoral component survival rate was 100% in both groups at 17 years; at 17 years, the cemented tibial component survival rate was 100% and the cementless tibial component 98.7%. No osteolysis was identified in either group.

CONCLUSION

Long-term results of both cementless and cemented TKAs were encouraging in patients with OA who were <55 years. However, we found no evidence to prove the superiority of cementless over cemented TKAs.