Cementless total knee arthroplasty

Robotic assistance improves success of cementless component fixation in one total knee arthroplasty system

INTRODUCTION

New cementless implant designs in total knee arthroplasty (TKA) have begun to shift the longstanding practice of cemented fixation. With aseptic loosening a leading cause for revision of cementless implants, initial osteointegration is critical for component survivorship. Robotic-assisted TKA (RA-TKA) has shown promising results in recent literature at improving component accuracy. The current study aims to evaluate if robotic assistance affects the success of cementless fixation in primary TKA.

METHODS

445 cementless primary TKA components from one manufacturer implanted by five surgeons between June 2018 and October 2022 were retrospectively reviewed. Those with minimum one-year follow-up were analyzed. Femoral and tibial components were reviewed separately and grouped based on whether manual or RA-TKA from the same manufacturer was performed. Fisher's exact test was used to analyze if aseptic loosening rates were different between the two techniques.

RESULTS

373 (82%) cementless components from a single knee system were included. 146 femoral and 103 tibial components were implanted using RA-TKA, while 63 femoral and 61 tibial components were implanted manually. At a mean follow-up of 18 months (range, 12 to 51 months), successful fixation was achieved in 96.2% of all components. No femoral components from either group were revised due to aseptic loosening. Four manually implanted vs. no robotically assisted tibial components were revised due to aseptic loosening (6.6% vs 0.0%; P = 0.038).

CONCLUSION

The performance of modern cementless femoral components was excellent with or without robotic assistance, however RA-TKA improved the survivorship of the same system's cementless tibial component.

LEVEL OF EVIDENCE

Level III.

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.

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

BACKGROUND

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

METHODS

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

RESULTS

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

CONCLUSIONS

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

The current role of CT in total knee arthroplasty

Advanced 3D imaging and CT-based navigation have emerged as valuable tools to use in total knee arthroplasty (TKA), for both preoperative planning and the intraoperative execution of different philosophies of alignment. Preoperative planning using CT-based 3D imaging enables more accurate prediction of the size of components, enhancing surgical workflow and optimizing the precision of the positioning of components. Surgeons can assess alignment, osteophytes, and arthritic changes better. These scans provide improved insights into the patellofemoral joint and facilitate tibial sizing and the evaluation of implant-bone contact area in cementless TKA. Preoperative CT imaging is also required for the development of patient-specific instrumentation cutting guides, aiming to reduce intraoperative blood loss and improve the surgical technique in complex cases. Intraoperative CT-based navigation and haptic guidance facilitates precise execution of the preoperative plan, aiming for optimal positioning of the components and accurate alignment, as determined by the surgeon's philosophy. It also helps reduce iatrogenic injury to the periarticular soft-tissue structures with subsequent reduction in the local and systemic inflammatory response, enhancing early outcomes. Despite the increased costs and radiation exposure associated with CT-based navigation, these many benefits have facilitated the adoption of imaged based robotic surgery into routine practice. Further research on ultra-low-dose CT scans and exploration of the possible translation of the use of 3D imaging into improved clinical outcomes are required to justify its broader implementation.

Short-Term (6 Months or Less) Pain in Cemented versus Cementless Total Knee Arthroplasty: A Systematic Review and Meta-Analysis

BACKGROUND

Cementless total knee arthroplasty (TKA) has increased in popularity to potentially improve survivorship. Radiostereometric studies demonstrate increased component migration during the first 3 to 6 months in cementless constructs, generating concern for increased postoperative pain during early osseointegration. The purpose of this study was to evaluate short-term (≤ 6 months) pain and function in cemented versus cementless TKA. We hypothesized that cementless TKA patients report increased pain during the short-term (≤ 6 months) postoperative period.

METHODS

The MEDLINE, EMBASE, CINAHL, and Cochrane Libraries were searched for studies evaluating short-term (≤ 6 months) outcomes of cemented versus cementless primary TKA. Studies involving hybrid fixation were excluded. A meta-analysis was performed using standardized mean difference for primary outcomes (early postoperative pain) and weighted mean difference (WMD) for secondary outcomes (early postoperative function).

RESULTS

There were eleven studies included. There was no significant difference in acute postoperative pain between cemented and cementless TKA within 6 months of index TKA (standardized mean difference 0.08 in favor of cemented TKA; P = .10). Early postoperative forgotten joint scores (WMD 0.81; P = .81) and knee injury and osteoarthritis outcome scores for joint replacement (WMD 0.80 in favor of cemented TKA; P = .14) were also similar between groups.

CONCLUSIONS

There is no difference in short-term (≤ 6 months) pain or early function between patients receiving cemented and cementless TKA. This suggests that surgeons may utilize cementless TKA without fear of increased pain due to micromotion within 6 months of index arthroplasty. However, additional studies with uniform assessment methods are needed to further inform differences in short-term pain and early functional outcomes between cemented and cementless TKA.

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

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

The Effect of Cemented Implants Placed During Initial TKA on Surgical Time and Expenses in Revision TKA

INTRODUCTION

Revision total knee arthroplasty (rTKA) is a complex procedure that often requires the removal of previous implants. There is little information evaluating the difference between removing cemented or noncemented knee prostheses in revision surgeries. The purpose of this study was to determine whether removing cemented or noncemented implants would affect surgical time and expenses incurred during revision procedures.

METHODS

This retrospective cohort study used a single-institution database to identify 300 patients who underwent femoral and tibial implant rTKA from 2016 to 2022 because of mechanical complications (infection cases excluded). Radiographs and surgical reports were used to confirm whether the fixation technique was cemented (N = 243) or noncemented (N = 57). The primary outcomes were surgical time and surgery costs. Secondary outcomes included readmission rates, revision implants used, stem usage, and insurance type.

RESULTS

The average surgical time was 121 minutes for noncemented and 128 minutes for cemented procedures (P = 0.118). The 90-day readmission rates for each group were similar at 7.00% for the cemented cohort and 8.77% for the noncemented cohort (P = 0.643). For patients with Medicare Advantage, the respective surgery costs were $1,966 for noncemented and $1,968 for cemented TKA (P = 0.988). For patients with commercial insurance, the respective surgery costs were $4,854 for noncemented and $5,660 for cemented TKA (P = 0.330).

CONCLUSION

Primary knee fixation type, cemented or noncemented, did not appear to influence the surgical duration or surgical costs of both-implant revision knee surgery indicated for mechanical complications.

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.

Cementless total knee arthroplasty in young patients using tantalum trabecular implants results in significantly lower rates of aseptic loosening

Aims

The mean age of patients undergoing total knee arthroplasty (TKA) has reduced with time. Younger patients have increased expectations following TKA. Aseptic loosening of the tibial component is the most common cause of failure of TKA in the UK. Interest in cementless TKA has re-emerged due to its encouraging results in the younger patient population. We review a large series of tantalum trabecular metal cementless implants in patients who are at the highest risk of revision surgery.

Methods

A total of 454 consecutive patients who underwent cementless TKA between August 2004 and December 2021 were reviewed. The mean follow-up was ten years. Plain radiographs were analyzed for radiolucent lines. Patients who underwent revision TKA were recorded, and the cause for revision was determined. Data from the National Joint Registry for England, Wales, Northern Island, the Isle of Man and the States of Guernsey (NJR) were compared with our series.

Results

No patients in our series had evidence of radiolucent lines on their latest radiological assessment. Only eight patients out of 454 required revision arthroplasty, and none of these revisions were indicated for aseptic loosening of the tibial baseplate. When compared to data from the NJR annual report, Kaplan-Meier estimates from our series (2.94 (95% confidence interval (CI) 1.24 to 5.87)) show a significant reduction in cumulative estimates of revision compared to all cemented (4.82 (95% CI 4.69 to 4.96)) or cementless TKA (5.65 (95% CI 5.23 to 6.10)). Our data (2.94 (95% CI 1.24 to 5.87)) also show lower cumulative revision rates compared to the most popular implant (PFC Sigma Cemented Knee implant fixation, 4.03 (95% CI 3.75 to 4.33)). The prosthesis time revision rate (PTIR) estimates for our series (2.07 (95% CI 0.95 to 3.83)) were lower than those of cemented cases (4.53 (95% CI 4.49 to 4.57)) from NJR.

Conclusion

The NexGen trabecular (tantalum) cementless implant has lower revision rates in our series compared to all cemented implants and other types of cementless implants, and its use in younger patients should be encouraged.

24-Year-Old Patient with Klippel-Trenaunay Syndrome Underwent Cementless Robotic Cruciate-Retaining TKA: A Case Report

CASE

A 24-year-old man with Klippel-Trenaunay syndrome (KTS) presented with severe knee osteoarthritis unresponsive to conservative measures. Owing to end-stage, debilitating arthritic symptoms, surgery was pursued. Careful preoperative, multidisciplinary planning/treatment included magnetic resonance imaging to characterize the venous malformations throughout the right lower extremity, preoperative sclerotherapy, sirolimus, and robotic-assisted cementless total knee arthroplasty (TKA).

CONCLUSION

Cementless robotic-assisted TKA with selective patellar resurfacing can be a viable option for young KTS patients with severe osteoarthritis when a meticulous multidisciplinary approach, including sclerotherapy and advanced imaging, is undertaken to analyze vascular abnormalities, minimize surgical risks, preserve bone stock, and optimize outcomes.

The Current Epidemiology of Revision Total Knee Arthroplasty in the United States From 2016 to 2022

BACKGROUND

The number of revision total knee arthroplasties (TKAs) is projected to reach 268,200 cases annually by 2030 in the United States. The growing demand for revision TKA can be attributed to the successes of primary TKAs combined with an aging population, patient desires to remain active, as well as expanded indications for younger patients. Given the evolving nature of revision TKAs, an epidemiological analysis of: (1) etiologies; (2) demographics, including age and region; as well as (3) lengths of stay (LOS) offers a way to minimize the gap between appropriate understanding and effective intervention.

METHODS

From 2016 to 2022, a national, all-payer database was queried. Incidences and indications were analyzed for a total of 135,983 patients who had revision TKA procedures.

RESULTS

The most common etiologies for revision TKA procedures were infection (19.3%) and aseptic loosening (12.8%), followed by mechanical complications (7.9%). The largest age group was 65 to 74 years (34.9%) followed by 55 to 64 years (32.2%), then age >75 years (20.5%). The South had the largest total procedure cohort (39.8%), followed by the Midwest (28.6%), then the Northeast (18.6%), and the West (13.0%). The mean length of stay was 3.86 days (range, 1.0 to 15.0).

CONCLUSIONS

Our study details the current status of revision TKA through 2022. While infection and aseptic loosening remain leading causes, we found a low aseptic loosening rate of 12.8%.

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.

Trends and risk factors for readmissions following press-fit total knee arthroplasty for the treatment of end-stage osteoarthritis of the knee: a five-year analysis

INTRODUCTION

The development of new prostheses with improved osseointegration, bone preservation, and reduced cost has renewed interest in uncemented total knee arthroplasty (UCTKA). In the current study, we aimed to: (1) assess demographic data of patients who were and were not readmitted and (2) identify patient-specific risk factors associated with readmission.

METHODS

A retrospective query from the PearlDiver database was performed from January 1, 2015, to October 31, 2020. International Classification of Disease, Ninth Revision (ICD-9), ICD-10, or Current Procedural Terminology (CPT) coding was used to distinguish cohorts of patients who had osteoarthritis of the knee and underwent UCTKA. Patients readmitted within 90 days were classified as the study population, while those who were not readmitted were classified as control. A linear regression model was utilized to analyze readmission risk factors.

RESULTS

The query yielded 14,575 patients, with 986 (6.8%) being readmitted. Patient demographics such as age (P < 0.0001), sex (P < 0.009), and comorbidity (P < 0.0001) were associated with annual 90-day readmission. Patient-specific risk factors associated with 90-day readmission following press-fit total knee arthroplasty were: arrhythmia (OR: 1.29, 95% CI: 1.11-1.49, P < 0.0005), coagulopathy (OR: 1.36, 95% CI: 1.13-1.63, P < 0.0007), fluid and electrolyte abnormalities (OR: 1.59, 95% CI: 1.38-1.84, P < 0.0001), iron deficiency anemia (OR: 1.49, 95% CI: 1.27-1.73, P < 0.0001), and obesity (OR: 1.37, 95% CI: 1.18-1.60, P < 0.0001).

DISCUSSION

This study demonstrates that patients with comorbidities, such as fluid and electrolyte problems, iron deficiency anemia, and obesity, were at an increased risk of readmission after having an uncemented total knee replacement. The risks of readmission following an uncemented total knee arthroplasty can be discussed with patients who have certain comorbidities by arthroplasty surgeons.

Fostering Excellence in Knee Arthroplasty: Developing Optimal Patient Care Pathways and Inspiring Knowledge Transfer of Advanced Surgical Techniques

Osteoarthritis of the knee is common. Early sports trauma or cartilage defects are risk factors for osteoarthritis. If conservative treatment fails, partial or total joint replacement is often performed. A joint replacement aims to restore physiological biomechanics and the quality of life of affected patients. Total knee arthroplasty is one of the most performed surgeries in musculoskeletal medicine. Several developments have taken place over the last decades that have truly altered the way we look at knee arthroplasty today. Some of the fascinating aspects will be presented and discussed in the present narrative review.

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.

Cementless Compared to Cemented Total Knee Arthroplasty is Associated With More Revisions Within 1 Year of Index Surgery

Background

Cementless total knee arthroplasties (TKAs) have gained renewed interest due to improved implant designs and lower rates of revision than its cemented counterparts. The purpose of this study was to compare revision rates between cemented vs cementless TKAs within 1 year of primary arthroplasty.

Methods

This was a retrospective review from the PearlDiver Patient Record Database. International Classification of Diseases and Current Procedural Terminology codes were used to identify patients who had undergone cemented and cementless TKAs and subsequent surgical revisions. An unadjusted univariate analysis of patient demographics, Charlson Comorbidity Index score, and surgical revisions at 90 days and 1 year after TKA was performed using chi-squared testing. Multivariate logistic regression analyses were subsequently performed for 1-year surgical complications requiring revision.

Results

Of 324,508 patients, 312,988 (96.45%) underwent cemented TKAs, and 11,520 (3.55%) underwent cementless TKAs. Patients undergoing cementless TKA tended to be younger than patients undergoing cemented TKA (63.67 ± 9.15 cementless vs 66.22 ± 8.85 cemented, P < .001). Univariate chi-squared testing showed that cementless patients were more likely to require 1-component femoral or tibial revision at 90 days and 1 year, irrigation and debridement at 90 days and 1 year, and arthroscopy with lysis of adhesions at 1 year only. Similar findings were observed for these 3 revision procedures at 1 year after correcting for age, gender, and Charlson Comorbidity Index score using multivariate logistic regression analysis as cementless TKA patients had higher odds ratios for each of the revisions.

Conclusions

Small but significant differences were found in surgical revisions among cementless TKAs when compared to cemented TKAs within 1 year of the index procedure.

Cementless Mobile-Bearing Total Knee Arthroplasty: 10 Years Follow-Up

Background Although most TKR surgeries are cemented, the interest in cementless TKR has increased dramatically during the last few years because of the new generation of cementless prostheses and the increased number of young patients who need TKR. Methods Ten years of retrospective reviews of 80 patients who had cementless, complete rotating platform TKR (DePuy Synthes, Warsaw, Indiana) were performed. Patients were divided into two groups according to their age (above and below 70 years old). Functional outcomes at the final follow-up were evaluated clinically by filling out a satisfaction form, and the Oxford Knee Score as well as all medical and surgical complications were recorded for each patient. Results The 10-year cumulative implant survival rate was 100%, i.e. no patients had revision surgeries with no significant statistical difference between the two age groups. The 10-year evaluation rate was 90%. Conclusion The use of cementless TKA exhibited good survivability, long-term clinical and functional results, and no implant revision in various age groups, as well as a high satisfaction rate. There was no statistically significant difference between the results of different age groups.

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.

Uncemented Tibial Fixation Has Comparable Prognostic Outcomes and Safety Versus Cemented Fixation in Cruciate-Retaining Total Knee Arthroplasty: A Meta-Analysis of Randomized Controlled Trials

BACKGROUND

Cemented and uncemented fixation are the primary methods of tibial prosthesis fixation in total knee arthroplasty. However, the optimal fixation method remains controversial. This article explored whether uncemented tibial fixation has better clinical and radiological outcomes, fewer complications, and revision rates compared to cemented tibial fixation.

METHODS

We searched the PubMed, Embase, Cochrane Library, and Web of Science databases up to September 2022 to identify randomized controlled trials (RCTs) that compared uncemented total knee arthroplasty (TKA) and cemented TKA. The outcome assessment consisted of clinical and radiological outcomes, complications (aseptic loosening, infection, and thrombosis), and revision rate. Subgroup analysis was used to explore the effects of different fixation methods on knee scores in younger patients.

RESULTS

Nine RCTs were finally analyzed with 686 uncemented knees and 678 cemented knees. The mean follow-up time was 12.6 years. The pooled data revealed significant advantages of uncemented fixations over cemented fixations in terms of the Knee Society Knee Score (KSKS) (p = 0.01) and the Knee Society Score-Pain (KSS-Pain) (p = 0.02). Cemented fixations showed significant advantages in maximum total point motion (MTPM) (p < 0.0001). There was no significant difference between uncemented fixation and cemented fixation regarding functional outcomes, range of motion, complications, and revision rates. When comparing among young people (<65 years), the differences in KSKS became statistically insignificant. No significant difference was shown in aseptic loosening and the revision rate among young patients.

CONCLUSIONS

The current evidence shows better knee score, less pain, comparable complications and revision rates for uncemented tibial prosthesis fixation, compared to cemented, in cruciate-retaining total knee arthroplasty.

Medial pivot total knee arthroplasty: Mid-term results

This study aims to evaluate the mid-term results of patients who underwent medial pivot total knee arthroplasty at a single center. A total of 304 knees of 236 patients (40 males, 196 females; mean operation age and standard deviation : 66,64 ±7,09 years; range, 45 to 82 years) treated with medial pivot total knee prosthesis in our center between January 2010 and December 2014 were retrospectively analyzed. The American Knee Society Score, Oxford Knee Score, and especially flexion angles were recorded during pre- and postoperative follow-up. Of the operated knees, 71.2% were unilateral and 28.8% were bilateral. The mean follow-up was 79.30±14.76 months. The postoperative results with the Functional Score, Knee Score, Oxford Score, Total Knee Society Score, and flexion angles were significantly higher compared to baseline (p<0.01). All postoperative scores were significantly lower inpatients aged ≥65years, compared to those aged <65 years (p<0.01). In patients who underwent resection of anterior and posterior the cruciate ligaments, only the mean flexion angles were found to increase (p<0.01). Our study results suggest that medial pivot knee prostheses are reliable in the mid-term and provide favorable results in terms of function and patient satisfaction. Level of Evidence: Level IV retrospective study.

Artificial Intelligence Radiographic Analysis Tool for Total Knee Arthroplasty

BACKGROUND

The postoperative follow-up of a patient after total knee arthroplasty (TKA) requires regular evaluation of the condition of the knee through interpretation of X-rays. This rigorous analysis requires expertize, time, and methodical standardization. Our work evaluated the use of an artificial intelligence tool, X-TKA, to assist surgeons in their interpretation.

METHODS

A series of 12 convolutional neural networks were trained on a large database containing 39,751 X-ray images. These algorithms are able to determine examination quality, identify image characteristics, assess prosthesis sizing and positioning, measure knee-prosthesis alignment angles, and detect anomalies in the bone-cement-implant complex. The individual interpretations of a pool of senior surgeons with and without the assistance of X-TKA were evaluated on a reference dataset built in consensus by senior surgeons.

RESULTS

The algorithms obtained a mean area under the curve value of 0.98 on the quality assurance and the image characteristics tasks. They reached a mean difference for the predicted angles of 1.71° (standard deviation, 1.53°), similar to the surgeon average difference of 1.69° (standard deviation, 1.52°). The comparative analysis showed that the assistance of X-TKA allowed surgeons to gain 5% in accuracy and 12% in sensitivity in the detection of interface anomalies. Moreover, this study demonstrated a gain in repeatability for each single surgeon (Light's kappa +0.17), as well as a gain in the reproducibility between surgeons (Light's kappa +0.1).

CONCLUSION

This study highlights the benefit of using an intelligent artificial tool for a standardized interpretation of postoperative knee X-rays and indicates the potential for its use in clinical practice.

Cementless Total Knee Arthroplasty Over the Past Decade: Excellent Survivorship in Contemporary Designs

BACKGROUND

Cementless fixation in total knee arthroplasty (TKA) is re-emerging due to improvements in biomaterials, surgical technique, and implant design. Albeit rare, failure of osseointegration typically occurs within the first 2 years, and limited data exist on survivorship of the modern cementless TKA designs. This study evaluated clinical survivorship of 2 contemporary cementless TKA designs at minimum 2-year follow-up.

METHODS

A total of 627 cementless TKAs were performed up to July 2022. Three hundred thirty-nine cases were eligible for 2-year follow-up. Indications centered around bone quality and involved predominantly younger patients. The 2 designs consisted of tibial components with a highly porous titanium ingrowth surface, a central keel, and peripheral cruciform pegs with a porous cobalt-chromium femur. Survivorship estimates were calculated using right-censored non-parametric Kaplan-Meier methodologies. A total of 226 TKAs obtained minimum 2-year follow-up with a mean of 3.6 years (range, 2 to 10).

RESULTS

The all-cause revision rate was 2.4% (8 of 339). The revision rate due to aseptic loosening was 0.6% (2 of 339) consisting of 2 femoral components. No tibial components were revised for aseptic loosening. Kaplan-Meier survivorship free from aseptic loosening was 99% (95% confidence interval 98 to 100) at a maximum of 10 years.

CONCLUSION

These results demonstrate encouraging survivorship of cementless fixation in primary TKA with use of contemporary ingrowth biomaterials and modern implant designs. This particular tibial implant design with a highly porous titanium fixation surface, central keel, and peripheral cruciform pegs demonstrated excellent clinical survivorship without failure which may portend superior fixation.

LEVEL OF EVIDENCE

IV-case series, no control group/historical control group.

Surgical accuracy and clinical outcomes of image-free robotic-assisted total knee arthroplasty

BACKGROUND

The development of total knee arthroplasty (TKA) for knee osteoarthritis (OA) has a good reputation for its effectiveness in reducing joint pain and improving range of motion. We aimed to review our early results using the image-free robotic-assisted technology in knee arthroplasty.

METHODS

A total of 71 patients suffering from end-stage OA knee receiving TKA operated by robotic-assisted surgery between the years 2018 and mid-2021 were recruited. Clinical and radiological outcomes were compared with age and sex-matched control group (conventional TKA).

RESULTS

The radiological outcome showed significantly more postoperative lower limb alignment outliers in conventional side than robotic-assisted sides. Postoperative knee scores were similar among both groups. Robotic-assisted TKA required a longer implantation time but a shorter hospital stay.

CONCLUSION

Robotic-assisted TKA achieved a lower rate of mechanical axis Outlier in the coronal and sagittal plane with a shorter hospital stay. Yet both methods achieve a similar functional outcome.

Long-Term Clinical Performance of an Uncemented, Mobile Bearing, Anterior Stabilized Knee System and the Impact of Previous Knee Surgery

BACKGROUND

The aim of this study is to report long-term survival and patient-reported outcome measures (PROMs) of the uncemented low contact stress total knee system and explore the potential association between prior knee surgery and outcomes.

METHODS

A total of 1,289 procedures in 1,068 patients performed between 2000 and 2010 (mean follow-up 11.1 years) were retrospectively identified. All patients received an uncemented, mobile bearing, anterior stabilized (cruciate sacrificing) knee implant with a porous coating on the bone-prosthesis surface. Implant survival was calculated using competing risk analyses at 5, 10, and 15 years. PROMs include the Oxford Knee Score, Knee Society Score (domain function), EuroQol 5D-3L, and Numeric Rating Scale for pain during rest and activity, and for overall satisfaction. The association between previous surgery (no surgery versus meniscectomy versus arthroscopy versus corrective osteotomies) and implant survival was assessed with multivariable Cox proportional hazards analysis; the association with PROMs was assessed with multivariable linear regression analyses.

RESULTS

Survival after 5, 10, and 15 years was 97.0% (95% CI 96.0-98.0), 96.3% (95% CI 95.3-97.3), and 96.0% (95% CI 94.8-97.2), respectively. The most common reason for revision was aseptic loosening of the tibial tray (23/49 revisions, 47%). All PROMs were comparable with the reference values of the Dutch Arthroplasty Register. History of knee surgery prior to TKA was not associated with survival or PROMs.

CONCLUSION

The low contact stress uncemented mobile bearing knee implant provides excellent survival and patient satisfaction in our cohort. Previous surgery does not seem to compromise results in our population.

Press-Fit Dual-Pivot Total Knee Arthroplasty: Early Results With a Minimum 2-Year Follow-Up

BACKGROUND

Ultracongruent (UC) tibial bearings are being used with increasing frequency in the United States. Evidence suggests that the use of certain UC bearings may lead to improved patient satisfaction when compared with using conventional inserts. However, little is known as to what effect the use of UC tibial inserts has on bone ingrowth in uncemented total knee arthroplasty (TKA). The purpose of this study was to determine the early clinical and radiographic results of TKA using a press-fit dual-pivot design.

METHODS

Between 2017 and 2019, a consecutive series of 232 TKAs were implanted using a press-fit tibial and femoral component and a UC dual-pivot tibial insert. Sixty-two percent of patients were male. The average age was 56 years. Patients were followed for a minimum of 2 years (range, 24-42 months) using KOOS-JR and Knee Society clinical and radiographic evaluation.

RESULTS

No patient had more than mild knee stiffness at the final follow-up. Two patients reported moderate knee pain with stair climbing. All other patients reported either mild or no pain with activity. Knee Society pain scores averaged 42 points. Flexion averaged 118 degrees. Three knees (1.3%) were revised (one each for flexion instability, tibial plateau fracture, and suspected femoral component loosening). No other cases of femoral or tibial loosening were identified.

CONCLUSION

Although the success of uncemented TKA is determined by a variety of factors, the use of this dual-pivot knee design did not appear to influence tibial or femoral component fixation at early follow-up, yielding acceptable clinical and radiographic outcomes.

Patella Strength Characteristics in Cemented vs Press-fit Implants: A Biomechanical Analysis of Initial Stability

Background

Patellar resurfacing is routinely performed during total knee arthroplasty to reduce pain associated with patellofemoral osteoarthritis. With 3-dimensional ingrowth materials readily available, the present study aimed to evaluate if cemented polyethylene (CP) patellar buttons conferred higher ultimate load to failure than press-fit metal-backed (PF) buttons in axial compression.

Material and methods

Ten matched cadaveric and 20 composite patellae were resurfaced and implanted with either a PF or CP button. Biomechanical testing using an MTS machine was performed to measure the force required to generate a periprosthetic patella fracture. Mean load to failure and load to failure per 1-mm patellar thickness were compared with a paired and independent samples Students’ t-test for the cadaveric and composite patellae, respectively.

Results

The average load to failure for the matched cadaveric patellae with PF implants was significantly lower than that for patellae with CP buttons (4082.05 N vs 5898.37 N, P = .045). The average load to failure for composite patella with PF implants was significantly higher than that for composite patellae with CP implants (6004.09 N vs 4551.40 N, P = .001). The mean load to failure per 1-mm patellar thickness was also significantly higher for composite patellae with PF implants (263.80 N/mm vs 200.37 N/mm, P = .001).

Conclusion

Cadaveric patellae with cemented implants had a significantly higher ultimate load to failure in axial compression than press-fit patella. However, this result was reversed in the composite model. Exploration of biological and composite model properties could provide further insight into patellar implant selection during total knee arthroplasty.

Cemented Versus Noncemented Total Knee Arthroplasty Outcomes

INTRODUCTION

Aseptic loosening remains one of the most common indications for revision total knee arthroplasty (TKA). Given the demographic shift to a younger and more active TKA patient population, some surgeons have revisited noncemented fixation given its potential for lower rates of long-term aseptic loosening. The purpose of this study was to compare the demographics and complications between patients undergoing noncemented and cemented TKA.

METHODS

Using the MKnee subset of the PearlDiver database, diagnosis and procedure codes were used to identify patients who had undergone cemented or noncemented TKA for osteoarthritis with a minimum 2-year follow-up. Propensity score matching was done to compare risk-adjusted medical and surgical complication profiles at 90 days, 1 year, and 2 years.

RESULTS

Of 203,574 patients identified, 3.2% underwent noncemented TKA and 96.8% underwent cemented TKA. Using propensity-matched analysis, there was no difference in 90-day medical complications. Noncemented TKA was associated with a greater risk of periprosthetic joint infection throughout the study (90-day odds ratio [OR] 1.34, 1-year OR 1.27, 2-year OR 1.27, P < 0.05). Noncemented TKA was associated with a greater risk of periprosthetic fracture at 1 year and 2 years (1 year OR 2.19, 2 years OR 1.89, P < 0.05). No notable difference was observed in risk of aseptic loosening between the two groups.

DISCUSSION

Noncemented TKA is associated with a higher rate of periprosthetic joint infection and periprosthetic fracture. Additional studies are needed to compare long-term rates of aseptic loosening between noncemented and cemented TKA.

LEVEL OF EVIDENCE

Level III.

A Matched Comparison of the Long-Term Outcomes of Cemented and Cementless Total Knee Replacements: An Analysis from the National Joint Registry of England, Wales, Northern Ireland and the Isle of Man

BACKGROUND

Total knee replacements (TKRs) can be implanted with or without the use of cement. It is currently uncertain how cemented and cementless TKRs compare overall and in different age groups of the population in the long term.

METHODS

The National Joint Registry collects information on knee replacements inserted in England, Wales, Northern Ireland, and the Isle of Man and was linked for multiple confounders to the National Health Service Hospital Episode Statistics database. With use of propensity score matching techniques, 44,954 cemented and cementless TKRs were compared. Regression models were used to compare the outcomes of revision, reoperation, and mortality both overall and in different age strata.

RESULTS

The 10-year implant survival rate with revision as the end point for cemented and cementless TKRs was 96.0% and 95.5%, respectively (hazard ratio [HR] = 1.14; p = 0.01). The 10-year survival rate with reoperation as the end point was 82.7% and 81.4%, respectively (HR = 1.08; p = 0.001). The rate of revision for pain was higher for cementless TKRs (0.5% [cemented] compared with 0.7% [cementless]; p = 0.002), but the rate of revision for infection was lower (0.7% [cemented] compared with 0.5% [cementless]; p = 0.003). No significant interactions with age existed for the outcomes of revision (p = 0.24), reoperation (p = 0.30), or mortality (p = 0.58).

CONCLUSIONS

We found that matched cemented and cementless TKRs both have 10-year implant survival rates of >95%. Cementless TKRs had a higher revision rate (absolute difference, 0.5%) and reoperation rate (absolute difference, 1.3%). The rate of revision for infection was lower in the cementless group, although the rate of revision for pain was higher. Age did not significantly affect the relative performances.

LEVEL OF EVIDENCE

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

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.

Cementless unicompartmental knee replacement achieves better ten-year clinical outcomes than cemented: a systematic review

PURPOSE

The aim of this study was to report and compare the long-term revision rate, revision indications and patient reported outcome measures of cemented and cementless unicompartmental knee replacements (UKR).

METHODS

Databases Medline, Embase and Cochrane Central of Controlled Trials were searched to identify all UKR studies reporting the ≥ 10 year clinical outcomes. Revision rates per 100 component years [% per annum (% pa)] were calculated by fixation type and then, subgroup analyses for fixed and mobile bearing UKRs were performed. Mechanisms of failure and patient reported outcome measures are reported.

RESULTS

25 studies were eligible for inclusion with a total of 10,736 UKRs, in which there were 8790 cemented and 1946 cementless knee replacements. The revision rate was 0.73% pa (CI 0.66-0.80) and 0.45% pa (CI 0.34-0.58) per 100 component years, respectively, with the cementless having a significantly (p < 0.001) lower overall revision rate. Therefore, based on these studies, the expected 10-year survival of cementless UKR would be 95.5% and cemented 92.7%. Subgroup analysis revealed this difference remained significant for the Oxford UKR (0.37% pa vs 0.77% pa, p < 0.001), but for non-Oxford UKRs there were no significant differences in revision rates of cemented and cementless UKRs (0.57% pa vs 0.69% pa, p = 0.41). Mobile bearing UKRs had significantly lower revision rates than fixed bearing UKRs in cementless (p = 0.001), but not cemented groups (p = 0.13). Overall the revision rates for aseptic loosening and disease progression were significantly lower (p = 0.02 and p = 0.009 respectively) in the cementless group compared to the cemented group (0.06 vs 0.13% pa and 0.10 vs 0.21% pa respectively).

CONCLUSIONS

Cementless fixation had reduced long-term revision rates compared to cemented for the Oxford UKR. For the non-Oxford UKRs, the revision rates of cementless and cemented fixation types were equivalent. Therefore, cementless UKRs offer at least equivalent if not lower revision rates compared to cemented UKRs.

LEVEL OF EVIDENCE

III.

Unicompartmental Knee Arthroplasty: Survivorship and Risk Factors for Revision: A Population-Based Cohort Study with Minimum 10-Year Follow-up

BACKGROUND

Operative management for end-stage knee osteoarthritis (OA) primarily consists of arthroplasty. Total knee arthroplasty (TKA) is the so-called gold standard for multicompartmental OA. In selected patients, specifically those with unicompartmental OA and no definite contraindications, realignment osteotomies and unicompartmental knee arthroplasty (UKA) are viable options. UKA offers several advantages over TKA, including preservation of both cruciate ligaments, faster recovery, and less osseous resection. The purpose of this study was to determine the survivorship of UKAs and risk factors for all-cause revision surgery in patients with a minimum follow-up of 10 years in a large population-based database.

METHODS

We performed a population-based cohort study using linked administrative databases in Ontario, Canada. We identified all UKAs performed from January 2002 through December 2006. All patients had a minimum 10-year follow-up. Demographic data and outcomes were summarized using descriptive statistics. We used a Cox proportional hazards model with the Fine and Gray method accounting for competing risks such as death to analyze the effect of surgical and patient factors on the risk of revision of UKA.

RESULTS

A total of 4,385 patients were identified as having undergone primary UKA from 2002 through 2006 in Ontario. Of these patients, 779 underwent revision surgery, for a cumulative risk for all-cause revision of 16.5% at 10 years (95% confidence interval [CI]: 15.4% to 17.7%). Mechanical loosening was the reason for 83.4% of all revisions. Male sex, diabetes, an age younger than 50 years, and cementless implants were significant risk factors for revision surgery. Residence in a rural or urban setting, income quintile, discharge destination, and type of OA were not associated with the risk of revision. Survivorship at 1, 5, 10, and 15 years was 97.2%, 90.5%, 83.5%, and 81.9%, respectively.

CONCLUSIONS

This study demonstrated a >80% long-term survivorship for UKA based on a large administrative database sample and identified important risk factors for failure including male sex, younger age, diabetes, and cementless fixation. This study found rates of survivorship similar to those previously reported in the literature, while identifying key risk factors for failure. Patient selection has always been identified as a key factor in ensuring successful UKA, and the risk factors identified in this study may help guide decision-making for surgeons and patients dealing with unicompartmental knee OA.

LEVEL OF EVIDENCE

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

The Impact of the Largest National Joint Registry on Current Knee Replacement Longevity Estimates: An Analysis and Review of Knee Prosthesis Brand and Fixation Technique

BACKGROUND

The UK National Joint Registry is the single largest joint registry in the world enrolling 1.3 million patients and recently reaching 17 years of follow-up data. Current knee prosthesis longevity estimates are based off smaller sized international registries and the impact of fixation type on prosthesis survival remains unclear.

METHODS

We used the UK National Joint Registry 17th annual report to calculate pooled mean survival estimates of total knee replacements (TKRs), unicondylar knee replacements (UKRs), and patellofemoral knee replacements at 10 and 15 years based on both construct brand and fixation technique (cemented vs uncemented). Independent t-testing was performed for significance.

RESULTS

All-cause survivorship of TKRs at 10 and 15 years is 96.7% and 95.4%, respectively. For UKRs it is 89.8% and 80.7% and for patellofemoral knee replacements it is 81.6% and 76.5%. In regard to fixation technique, cemented and uncemented TKRs show similar survivorship at both time points. For UKRs uncemented constructs showed improved survivorship compared to cemented at 10 years (92.7% vs 88.2%, P < .001). This was greatest among those <65 years of age. In fact, all construct types regardless of fixation showed increased rate of revision in those <65 years vs those ≥65 years.

CONCLUSION

We provide more accurate estimations for knee prosthesis survival and highlight that younger patients, particularly those receiving UKRs, are prone to greater revision risks. This data also suggests that uncemented fixation may offer improved joint survival in these patients.

Risk of revision for medial unicompartmental knee arthroplasty according to fixation and bearing type : short- to mid-term results from the Dutch Arthroplasty Register

AIMS

Uncemented mobile bearing designs in medial unicompartmental knee arthroplasty (UKA) have seen an increase over the last decade. However, there are a lack of large-scale studies comparing survivorship of these specific designs to commonly used cemented mobile and fixed bearing designs. The aim of this study was to evaluate the survivorship of these designs.

METHODS

A total of 21,610 medial UKAs from 2007 to 2018 were selected from the Dutch Arthroplasty Register. Multivariate Cox regression analyses were used to compare uncemented mobile bearings with cemented mobile and fixed bearings. Adjustments were made for patient and surgical factors, with their interactions being considered. Reasons and type of revision in the first two years after surgery were assessed.

RESULTS

In hospitals performing less than 100 cases per year, cemented mobile bearings reported comparable adjusted risks of revision as uncemented mobile bearings. However, in hospitals performing more than 100 cases per year, the adjusted risk of revision was higher for cemented mobile bearings compared to uncemented mobile bearings (hazard ratio 1.78 (95% confidence interval 1.34 to 2.35)). The adjusted risk of revision between cemented fixed bearing and uncemented mobile bearing was comparable, independent of annual hospital volume. In addition, 12.3% of uncemented mobile bearing, 20.3% of cemented mobile bearing, and 41.5% of uncemented fixed bearing revisions were for tibial component loosening. The figures for instability were 23.6%, 14.5% and 11.7%, respectively, and for periprosthetic fractures were 10.0%, 2.8%, and 3.5%. Bearing exchange was the type of revision in 40% of uncemented mobile bearing, 24.3% of cemented mobile bearing, and 5.3% cemented fixed bearing revisions.

CONCLUSION

The findings of this study demonstrated improved survival with use of uncemented compared to cemented mobile bearings in medial UKA, only in those hospitals performing more than 100 cases per year. Cemented fixed bearings reported comparable survival results as uncemented mobile bearings, regardless of the annual hospital volume. The high rates of instability, periprosthetic fractures, and bearing exchange in uncemented mobile bearings emphasize the need for further research. Cite this article: Bone Joint J 2021;103-B(7):1261-1269.

Cementless Fixation in Primary Total Knee Arthroplasty: Historical Perspective to Contemporary Application

Cemented total knee arthroplasty (TKA) has been considered the benchmark, with excellent clinical outcomes and low rates of aseptic loosening at the long-term follow-up. However, alterations of the bone/cement interface leading to aseptic loosening, particularly in younger and obese patients, along with increased life expectancy have led to a renewed interest in noncemented TKA fixation. Certain early noncemented designs exhibited higher rates of subsidence and component failure. Improvements in designs, materials, and surgical technique offer promise for improved results with contemporary noncemented TKA applications. In an increasing cost-conscious healthcare environment, implant cost is important to consider because press-fit prostheses are generally more expensive. However, this cost may be offset by shorter surgical times, cement costs, and the potential for osseous integration. Technological advances have improved the manufacturing of porous metals, with reported excellent midterm survivorship. Future prospective, randomized trials, and registry data are needed to delineate differences between cemented and noncemented fixation, survivorship, and patient-reported outcomes, especially in young, functionally active, and/or obese populations.

Variation and trends in reasons for knee replacement revision: a multi-registry study of revision burden

Background and purpose - Studies describing time-related change in reasons for knee replacement revision have been limited to single regions or institutions, commonly analyze only 1st revisions, and may not reflect true caseloads or findings from other areas. We used revision procedure data from 3 arthroplasty registries to determine trends and differences in knee replacement revision diagnoses.Patients and methods - We obtained aggregated data for 78,151 revision knee replacement procedures recorded by the Swedish Knee Arthroplasty Register (SKAR), the Australian Orthopaedic Association National Joint Replacement Registry (AOANJRR), and the Kaiser Permanente Joint Replacement Registry (KPJRR) for the period 2003-2017. Equivalent diagnosis groups were created. We calculated the annual proportions of the most common reasons for revision.Results - Infection, loosening, and instability were among the 5 most common reasons for revision but magnitude and ranking varied between registries. Over time there were increases in proportions of revisions for infection and decreases in revisions for wear. There were inconsistent proportions and trends for the other reasons for revision. The incidence of revision for infection showed a uniform increase.Interpretation - Despite some differences in terminology, comparison of registry-recorded revision diagnoses is possible, but defining a single reason for revision is not always clear-cut. There were common increases in revision for infection and decreases in revision for wear, but variable changes in other categories. This may reflect regional practice differences and therefore generalizability of studies regarding reasons for revision is unwise.

Preoperative activity levels are an important indicator of postoperative activity in cementless TKAs

Introduction

It is of interest if preoperative activity level has an impact on postoperative activity level following cementless TKA.

Methods

This review contained 127 patients who had a preoperative Lower Extremity Activity Scale (LEAS) score ≥ to 10 (active patients) and 121 patients <10 (inactive patients).

Results

Postoperatively, the results showed a difference in LEAS Activity (Active 10.5 vs. Inactive 8.7, p < 0.001). Active patients had a drop in their activity level by 1.2 on the LEAS score, yet inactive patients increased by 1.6 (p < 0.0001).

Conclusion

Preoperative activity levels are a good indicator for postoperative activity in cementless TKA.

Cemented vs. cementless fixation in primary total knee arthroplasty: a systematic review and meta-analysis

Over 100,000 total knee replacements (TKRs) are carried out in the UK annually, with cemented fixation accounting for approximately 95% of all primary TKRs. In Australia, 68.1% of all primary TKRs use cemented fixation, and only 10.9% use cementless fixation. However, there has been a renewed interest in cementless fixation as a result of improvements in implant design and manufacturing technology.

This meta-analysis aimed to compare the outcomes of cemented and cementless fixation in primary TKR. Outcome measures included the revision rate and patient-reported functional scores.

MEDLINE and EMBASE were searched from the earliest available date to November 2018 for randomized controlled trials of primary TKAs comparing cemented versus cementless fixation outcomes.

Six studies met our inclusion criteria and were analysed. A total of 755 knees were included; 356 knees underwent cemented fixation, 399 underwent cementless fixation. They were followed up for an average of 8.4 years (range: 2.0 to 16.6).

This study found no significant difference in revision rates and knee function in cemented versus cementless TKR at up to 16.6-year follow-up.

Cite this article: EFORT Open Rev 2020;5:793-798. DOI: 10.1302/2058-5241.5.200030

Early clinical outcome and learning curve following unilateral primary total knee arthroplasty after introduction of a novel total knee arthroplasty system

BACKGROUND

New implants for total knee arthroplasty (TKA) are continuously introduced with the proposed benefit of increased performance and improved outcome. Little information exists on how the introduction of a novel arthroplasty implant affects the perioperative and surgical outcome immediately after implementation.

AIM

To investigate how surgery-related factors and implant positioning were affected by the introduction of a novel TKA system.

METHODS

A novel TKA system was introduced at our institution on 30th November 2015. Seventy-five TKAs performed with the Persona TKA immediately following its introduction by 3 different surgeons (25 TKAs/surgeon) were identified as the Introduction Group. Moreover, the latest 25 TKAs performed by each surgeon prior to introduction of the Persona TKA were identified as the Control Group. A Follow-up Group of 25 TKAs/surgeon was identified starting 1-year after the end of the introduction period. Demographics, surgery-related factors and alignment data were recorded, and intergroup differences compared.

RESULTS

Following introduction of the novel implant, Persona TKA was utilized in 69% (71%), 53% (54%), and 45% (75%) of primary TKA procedures by the three surgeons, respectively (Follow-up Group). Mean surgery time was increased by 28% (P < 0.0001) and mean intra-operative blood loss by 25% (P = 0.002) in the Introduction Group, while only the mean surgery time was increased in the Follow-up Group by 18% (P < 0.0001). Overall alignment was similar between the groups apart from femoral flexion (FF) and tibial slope (TS). The number of FF outliers was reduced in the Introduction Group with a more pronounced decrease in the Follow-up Group.

CONCLUSION

Introduction of the new TKA implant increased surgical time and intraoperative blood loss immediately after its introduction. These differences diminished one year after introduction of the new implant. Fewer outliers with respect to FF and TS were seen when using the novel TKA implant. Further studies are needed to investigate if these differences persist over time and correlate with patient reported outcomes.

A matched cohort study between cementless TKA and cemented TKA shows a reduction in tourniquet time and manipulation rate

Introduction

Cementless total knee arthroplasty (TKA) is now becoming more acceptable with the advent of newer ongrowth constructs and better initial fixation. It has been proposed that cementless TKA may save OR time and result in a lower incidence of manipulation. This study was designed to assess the difference between cemented and cementless TKA.

Methods

Our hospital statistician performed a matched cohort analysis between 127 cementless TKAs and 127 cemented TKRs performed by a single surgeon. Patients were matched on age and BMI. Mean tourniquet time between the cemented and cementless TKAs was assessed as well as the rate of manipulation between these groups. Of note, a tourniquet was routinely used in both the cementless and cemented cohorts to reduce confounding bias.

Results

A total of 127 cementless TKAs with a mean age of 60.8 years and mean BMI 32.2 were compared to 127 cemented TKAs with a mean age of 61.5 years and mean BMI of 32.2 at an average follow-up of 2.0 years. There was a statistically significant reduction in tourniquet time in the cementless TKA cohort at 45.7 min compared to the cemented TKA cohort at 54.8 min (p = 0.001). Estimated blood loss was similar in both the cementless (179.5 ml) and cemented (196 ml) cohorts (p = 0.3) and postoperative outcomes, including UCLA score.In addition, the cementless TKA cohort had a manipulation rate of 0% compared to 3.1% for the cemented TKA group (p = 0.044).

Discussion and conclusion

While cementless and cemented TKA have shown similar PROMs and survivorship, we demonstrated a significant reduction in tourniquet time with cementless TKRs, with similar estimated blood loss, and a lower incidence of manipulation with cementless TKRs in this matched cohort study. The increased cost of a cementless implant may be negated if one considers the cost savings of not using cement, the cost savings of not performing manipulations, and the shorter operative time.

F-actin Regulates Osteoblastic Differentiation of Mesenchymal Stem Cells on TiO2 Nanotubes Through MKL1 and YAP/TAZ

Titanium and titanium alloys are widely used in orthopedic implants. Modifying the nanotopography provides a new strategy to improve osseointegration of titanium substrates. Filamentous actin (F-actin) polymerization, as a mechanical loading structure, is generally considered to be involved in cell migration, endocytosis, cell division, and cell shape maintenance. Whether F-actin is involved and how it functions in nanotube-induced osteogenic differentiation of mesenchymal stem cells (MSCs) remain to be elucidated. In this study, we fabricated TiO₂ nanotubes on the surface of a titanium substrate by anodic oxidation and characterized their features by scanning electron microscopy (SEM), X-ray energy dispersive analysis (EDS), and atomic force microscopy (AFM). Alkaline phosphatase (ALP) staining, Western blotting, qRT-PCR, and immunofluorescence staining were performed to explore the osteogenic potential, the level of F-actin, and the expression of MKL1 and YAP/TAZ. Our results showed that the inner diameter and roughness of TiO₂ nanotubes increased with the increase of the anodic oxidation voltage from 30 to 70 V, while their height was 2 μm consistently. Further, the larger the tube diameter, the stronger the ability of TiO₂ nanotubes to promote osteogenic differentiation of MSCs. Inhibiting F-actin polymerization by Cyto D inhibited osteogenic differentiation of MSCs as well as the expression of proteins contained in focal adhesion complexes such as vinculin (VCL) and focal adhesion kinase (FAK). In contrast, after Jasp treatment, polymerization of F-actin enhanced the expression of RhoA and transcription factors YAP/TAZ. Based on these data, we concluded that TiO₂ nanotubes facilitated the osteogenic differentiation of MSCs, and this ability was enhanced with the increasing diameter of the nanotubes within a certain range (30-70 V). F-actin mediated this process through MKL1 and YAP/TAZ.

Long acting anti-infection constructs on titanium

Peri-prosthetic joint infections (PJI) are a serious adverse event following joint replacement surgeries; antibiotics are usually added to bone cement to prevent infection offset. For uncemented prosthesis, alternative antimicrobial approaches are necessary in order to prevent PJI; however, despite elution of drug from the surface of the device being shown one of the most promising approach, no effective antimicrobial eluting uncemented device is currently available on the market. Consequently, there is a clinical need for non-antibiotic antimicrobial uncemented prosthesis as these devices present numerous benefits, particularly for young patients, over cemented artificial joints. Moreover, non-antibiotic approaches are driven by the need to address the growing threat posed by antibiotic resistance. We developed a multilayers functional coating on titanium surfaces releasing chlorhexidine, a well-known antimicrobial agent used in mouthwash products and antiseptic creams, embedding the drug between alginate and poly-beta-amino-esters. Chlorhexidine release was sustained for almost 2 months and the material efficacy and safety was proven both in vitro and in vivo. The coatings did not negatively impact osteoblast and fibroblast cells growth and were capable of reducing bacterial load and accelerating wound healing in an excisional wound model. As PJI can develop weeks and months after the initial surgery, these materials could provide a viable solution to prevent infections after arthroplasty in uncemented prosthetic devices and, simultaneously, help the fight against antibiotic resistance.

Functional outcomes comparative analysis of cemented and uncemented total knee arthroplasty

Introduction

Cementless knee arthroplasty becomes more and more popular worldwide. At the beginning of endoprosthetics era, cementless implants showed unsatisfactory results. However, surgical technologies develop rapidly and nowadays the cementless fixation shows better outcomes.

Objectives

To analyze the experience of total knee arthroplasty using cementless fixation for the treatment of advanced arthritis of the knee.

Methods

We operated on 130 patients. The mean follow-up duration was 36 months. In 70 patients we used cementless fixation and in 60 patients we used implants with cemented fixation. To evaluate the results, we used KOOS scale and WOMAC scale. We also evaluated the mean duration of surgical intervention and blood loss.

Results

In the cementless group WOMAC and KOOS scales scores before the operation were 198,2 (±35.7) and 23,1 (±3.4), respectively, and in the cemented group it was 199.3(±36.8) and 24.9 (±2.1), respectively(p > 0,05). One year after the operation, KOOS and WOMAC scores were 54.5(±12.6) and 83.6(±8,.2) in the cementless group and 78.9(±4.6) and 66.9(±5.7) in the cemented group(p < 0,05)., respectively. Intraoperative blood loss was 255(±89,3) in the cemented group and 315(±52,1) in cementless group(p < 0,05). Postoperative blood loss was 515(±119, 5) and 440(±129,3)) (p < 0,05), respectively. Mean duration of intervention was 78 min (±6,8) in cemented group and 64 min (±8,7) in cementless group(p < 0,05).

Conclusions

1We have better functional results using implants with cementless fixation.2There was a greater intraoperative and postoperative blood loss in cementless group.3Cementless knee arthroplasty associated with shorter duration of intervention than cemented.

The Effect of Surgeon Caseload on the Relative Revision Rate of Cemented and Cementless Unicompartmental Knee Replacements: An Analysis from the National Joint Registry for England, Wales, Northern Ireland and the Isle of Man

BACKGROUND

Unicompartmental knee replacement (UKR) offers substantial benefits compared with total knee replacement (TKR) but is associated with higher revision rates. Data from registries suggest that revision rates for cementless UKR implants are lower than those for cemented implants. It is not known how much of this difference is due to the implant or to other factors, such as a greater proportion of high-volume surgeons using cementless implants. We aimed to determine the effect of surgeon caseload on the revision rate of matched cemented and cementless UKRs.

METHODS

From a group of 40,522 Oxford (Zimmer Biomet) UKR implants (30,814 cemented, 9,708 cementless) recorded in the National Joint Registry, 14,814 (7,407 cemented, 7,407 cementless) were propensity-score matched. Surgeons were categorized into 3 groups: low volume (<10 cases/year), medium volume (10 to <30 cases/year), and high volume (≥30 cases/year). The effect of caseload on the relative risk of revision was assessed with use of Cox regression.

RESULTS

The 10-year survival rates for unmatched cementless and cemented UKR implants were 93.3% (95% confidence interval [CI] = 89.8% to 95.7%) and 89.1% (95% CI = 88.6% to 89.6%), respectively, with the difference being significant (hazard ratio [HR] = 0.59; p < 0.001). Cementless UKR implants had a greater proportion of high-volume surgeon users than cemented implants (30.4% compared with 15.1%). Following matching, the 10-year survival rates were 93.2% (95% CI = 89.7% to 95.6%) and 90.2% (95% CI = 87.5% to 92.3%), which were still significantly different (HR = 0.76; p = 0.002). The 10-year survival rates for matched cementless and cemented UKR implants were 86.8% (95% CI = 73.6% to 93.7%) and 81.8% (95% CI = 73.0% to 88.0%) for low-volume surgeons, 94.3% (95% CI = 92.2% to 95.9%) and 92.5% (95% CI = 89.9% to 94.5%) for medium-volume surgeons, and 97.5% (95% CI = 96.5% to 98.2%) and 94.2% (95% CI = 90.8% to 96.4%) for high-volume surgeons. The revision rate for cementless implants was lower for surgeons in all 3 caseload groups (HR = 0.74, 0.79, 0.80, respectively).

CONCLUSIONS

Cementless fixation decreased the revision rate by about a quarter, whatever the surgeon caseload. Caseload had a profound effect on implant survival. Low-volume surgeons had a high revision rate with cemented or cementless fixation and therefore should consider either stopping or doing more UKR procedures. High-volume surgeons performing cementless UKR demonstrated a 10-year survival rate of 97.5%, which was similar to that reported in registries for the best-performing TKRs.

LEVEL OF EVIDENCE

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

The clinical outcomes of cementless unicompartmental knee replacement in patients with reduced bone mineral density

BACKGROUND

Osteoporosis and osteopenia are conditions characterised by reduced bone mineral density (BMD). There is concern that bone with reduced BMD may not provide sufficient fixation for cementless components which primarily rely on the quality of surrounding bone. The aim of our study was to report the midterm clinical outcomes of patients with reduced BMD undergoing cementless unicompartmental knee replacements (UKR). Our hypothesis was that there would be no difference in outcome between patients with normal bone and those with reduced BMD.

METHODS

From a prospective cohort of 70 patients undergoing cementless UKR surgery, patients were categorised into normal (n = 20), osteopenic (n = 38) and osteoporotic groups (n = 12) based on their central dual-energy X-ray absorptiometry (DEXA) scans according to the World Health Organization criteria. Patients were followed up by independent research physiotherapists and outcome scores; Oxford Knee Score (OKS), Tegner score, American Knee Society Score Functional (AKSS-F) and Objective (AKSS-O) were recorded preoperatively and at a mean of 4 years postoperatively. The prevalence of reoperations, revisions and mortality was also recorded at a mean of 5 years postoperatively.

RESULTS

There were no significant differences in the midterm postoperative OKS (P = 0.83), Tegner score (P = 0.17) and AKSS-O (P = 0.67). However, the AKSS-F was significantly higher (P = 0.04) in normal (90, IQR 37.5) compared to osteoporotic (65, IQR 35) groups. There were no significant differences (P = 0.82) between normal and osteopenic bone (80, IQR 35). The revision prevalence was 5%, 2.6% and 0% in the normal, osteopenic and osteoporotic groups respectively. The reoperation prevalence was 5%, 7.9% and 0% respectively. There were no deaths in any group related to the implant.

CONCLUSIONS

We found that patients with reduced BMD could safely undergo cementless UKR surgery and have similar clinical outcomes to those with normal BMD. However, larger studies with longer follow-up are needed to confirm our findings and ensure that cementless fixation is safe in patients with reduced BMD.

Cementless versus Cemented Fixation in Total Knee Arthroplasty: Usage, Costs, and Complications during the Inpatient Period

Cemented fixation has been the gold standard in total knee arthroplasty (TKA). However, with younger and more active patients requiring TKA, cementless (press-fit) fixation has sparked renewed interest. Therefore, we investigated differences in (1) patient demographics, (2) inpatient costs, (3) short-term complications, and (4) discharge disposition between patients who underwent TKA with cemented and cementless fixation. The National Inpatient Sample database was queried for TKA patients with cement or cementless fixation between October 1 and December 31, 2015. Primary outcomes of interest included complications, length of stay (LOS), discharge disposition, and inpatient costs. Student's t-test and chi-square analysis were used to assess continuous and categorical data, respectively. Multivariable analysis evaluated the effects of fixation type on the continuous and categorical dependent variables. Patients who received cementless fixation were more often younger (63.5 vs. 65.9 years), male (47.4 vs. 40.3%), Black (10.7 vs. 7.7%), from the Northeast census region (29.1 vs. 17.1%), and under private insurance (49.2 vs. 40.3%; p < 0.001 for all). Cementless fixation involved higher inpatient hospital costs (US$17,357 vs. US$16,888) and charges (US$67,366 vs. US$64,190; p < 0.001 for both), lower mean LOS (2.63 vs. 2.71 days; p < 0.001), and higher odds of being discharged to home (odds ratio = 1.99; p = 0.002). This study revisited the outcomes of TKA with cementless fixation and demonstrated higher inpatient charges and costs, shorter mean LOS, and higher odds of being discharged home. Future studies should investigate patient outcomes and complications past the inpatient period, evaluate long-term survivorship and failure rates, and implement a prospective study design.

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.].

The effect of implant modification: the low contact stress experience

AIMS

The aim of this study was to conduct the largest low contact stress (LCS) retrieval study to elucidate the failure mechanisms of the Porocoat and Duofix femoral component. The latter design was voluntarily recalled by the manufacturer.

MATERIALS AND METHODS

Uncemented LCS explants were divided into three groups: Duofix, Porocoat, and mixed. Demographics, polyethylene wear, tissue ingrowth, and metallurgical analyses were performed.

RESULTS

In 104 implants, a decrease in the odds of loosening and an increase in metallosis and tissue staining in the Duofix group relative to Porocoat group was detected (p = 0.028). There was an increased presence of embedded metallic debris in the Duofix group (p < 0.001). Decreased tissue ingrowth was associated with the Duofix surface (p < 0.001). The attached beads had reduced microhardness, indicative of adverse thermal processing, which resulted in bead shedding, particulate debris, and metallosis.

CONCLUSION

Hydroxyapatite coating of the LCS femoral component produced unexpected results and led to its recall. The root cause was likely a combination of retained alumina grit and a reduction in bead microhardness (mechanical strength) resulting in increased particle debris, metallosis, and early revision. The Duofix LCS femoral component was not equivalent to the Porocoat version despite its approval through the Food and Drug Administration (FDA) 510(k) equivalance approval process. Regulation of the introduction of modified existing devices needs to be improved and the Duofix LCS should have been considered to be a new device for which equivalence had not been demonstrated at the point of introduction. Cite this article: Bone Joint J 2019;101-B:1248-1255.

Nanoparticle-based model of anti-inflammatory drug releasing LbL coatings for uncemented prosthesis aseptic loosening prevention

Introduction

The only treatment for aseptic loosening is the replacement of the prosthesis through revision surgery. A preventive approach, achieved through anti-inflammatory drugs released from the device, has shown to be a viable strategy; however, the performance of these devices is not yet satisfactory thus further improvements are necessary.

Methods

We used titanium nanoparticles as a model for implant surfaces and developed a coating containing dexamethasone (DEX) using layer-by-layer deposition.

Results

The amount of deposited drug depended on the number of layers and the release was sustained for months. The efficiency of the released DEX in reducing inflammation markers (tumor necrosis factor alpha and IL-6) produced by human monocytes and macrophages was similar to the pure drug at the same concentration without negative impacts on the viability and morphology of these cells.

Conclusion

These coatings were not inferior to medical grade titanium (the standard material used in uncemented devices) regarding their ability to sustain osteoblasts and fibroblasts growth.

Classification of combined partial knee arthroplasty

AIMS

There has been a recent resurgence in interest in combined partial knee arthroplasty (PKA) as an alternative to total knee arthroplasty (TKA). The varied terminology used to describe these procedures leads to confusion and ambiguity in communication between surgeons, allied health professionals, and patients. A standardized classification system is required for patient safety, accurate clinical record-keeping, clear communication, correct coding for appropriate remuneration, and joint registry data collection.

MATERIALS AND METHODS

An advanced PubMed search was conducted, using medical subject headings (MeSH) to identify terms and abbreviations used to describe knee arthroplasty procedures. The search related to TKA, unicompartmental (UKA), patellofemoral (PFA), and combined PKA procedures. Surveys were conducted of orthopaedic surgeons, trainees, and biomechanical engineers, who were asked which of the descriptive terms and abbreviations identified from the literature search they found most intuitive and appropriate to describe each procedure. The results were used to determine a popular consensus.

RESULTS

Survey participants preferred "bi-unicondylar arthroplasty" (Bi-UKA) to describe ipsilateral medial and lateral unicompartmental arthroplasty; "medial bi-compartmental arthroplasty" (BCA-M) to describe ipsilateral medial unicompartmental arthroplasty with patellofemoral arthroplasty; "lateral bi-compartmental arthroplasty" (BCA-L) to describe ipsilateral lateral unicompartmental arthroplasty with patellofemoral arthroplasty; and tri-compartmental arthroplasty (TCA) to describe ipsilateral patellofemoral and medial and lateral unicompartmental arthroplasties. "Combined partial knee arthroplasty" (CPKA) was the favoured umbrella term.

CONCLUSION

We recommend bi-unicondylar arthroplasty (Bi-UKA), medial bicompartmental arthroplasty (BCA-M), lateral bicompartmental arthroplasty (BCA-L), and tricompartmental arthroplasty (TCA) as the preferred terms to classify CPKA procedures. Cite this article: Bone Joint J 2019;101-B:922-928.

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