Failure After Modern Total Knee Arthroplasty: A Prospective Study of 18,065 Knees

Safety and effectiveness of intraosseous regional prophylactic antibiotics in total knee arthroplasty: a systematic review and meta-analysis

BACKGROUND

Intraosseous regional administration (IORA) as a widely applicable and clinically valuable route of administration has gained significant attention in the context of total knee arthroplasty (TKA) for the prophylactic administration of antibiotics. However, there is still controversy regarding its effectiveness and safety. The latest meta-analysis reports that the use of IORA for antibiotics in TKA is as safe and effective as IV administration in preventing prosthetic joint infection (PJI), but they did not separate the statistics for primary TKA and revision TKA, which may be inappropriate. There is currently a lack of evidence specifically comparing the outcomes of prophylactic antibiotic administration via IORA or IV route in primary/revision TKA, respectively, and new research evidence has emerged.

PURPOSES

In this study, we conducted a systematic review and meta-analysis with the primary objective of comparing the local drug tissue concentration and the incidence of PJI between preoperative IORA and intravenous (IV) administration of prophylactic antibiotics in TKA. Additionally, the occurrence of complications between the two administration routes was also compared.

PATIENTS AND METHODS

This meta-analysis was conducted following the Preferred Reporting Items for Systematic Reviews and Meta-analyses statement (PRISMA) guidelines. Retrospective cohort studies and prospective randomized controlled trials that utilized intraosseous local drug delivery for prophylactic antibiotics in knee arthroplasty were included. English literature from PubMed, Embase, and Cochrane Library databases was searched from the inception of each database until December 2023. Two researchers independently screened the literature, assessed the quality, and extracted data according to the inclusion criteria. The primary outcomes were local antibiotic tissue concentration and postoperative PJI incidence, while the secondary outcome was the occurrence of postoperative complications. Statistical analysis was performed using Review Manager 5.3 software.

RESULTS

This study included 7 prospective randomized controlled trials and 5 retrospective cohort studies. A total of 4091 patients participated in the 12 included studies, with 1,801 cases receiving IORA and 2,290 cases in the control group. In terms of local drug tissue concentration, intraosseous infusion (IO) 500 mg vancomycin significantly increased the drug concentration in the periarticular adipose tissue (SMD: 1.36; 95% CI: 0.87-1.84; P < 0.001; I2 = 0%) and bone tissue (SMD: 0.94; 95% CI: 0.49-1.40; P < 0.001; I2 = 0%) compared to IV 1 g vancomycin. Regarding the incidence of postoperative PJI after primary TKA, IO 500 mg vancomycin was more effective in reducing the occurrence of PJI compared to IV 1 g vancomycin (OR: 0.19; 95% CI: 0.06-0.59; P < 0.001; I2 = 36%). Finally, no significant differences were found between the two groups in terms of postoperative pulmonary embolism (PE) (OR: 1.72; 95% CI: 0.22-13.69; P = 0.59; I2 = 0%) and vancomycin-related complications (OR: 0.54; 95% CI: 0.25-1.19; P = 0.44; I2 = 0%).

CONCLUSIONS

Preoperative prophylactic antibiotic administration via IORA in TKA significantly increases local drug tissue concentration without significantly increasing systemic drug-related complications compared to traditional IV administration. In primary TKA, low-dose vancomycin via IORA is more effective in reducing the incidence of PJI compared to traditional IV regimens. However, its effectiveness remains controversial in high-risk populations for PJI, such as obese, diabetic, and renal insufficiency patients, as well as in revision TKA.

A novel radiological index uses the inner canal diameter and the Citak classification index to predict risk factor for aseptic loosening following hinged total knee arthroplasty

INTRODUCTION

It remains unclear if distal femoral morphology should be a key consideration when selecting the implant or fixation strategy. A novel radiological index has been proposed to classify patients' distal femoral morphology. This study aims to evaluate the validity of this classification system in a cohort of patients undergoing hinged Total Knee Arthroplasty (TKA), and to determine if distal femoral morphology is a risk factor for aseptic loosening or all cause revision following hinged TKA.

MATERIALS AND METHODS

This study was a retrospective analysis of our institutional database. Fifty-nine patients having undergone hinged TKA with adequate radiographs for examination were eligible for inclusion. Radiographic measurements were performed using the Citak radiological index criteria. The proportion of aseptic loosening and all-cause revisions were compared between the different classification groups.

RESULTS

The analysis included 41 females (69.5%) and 18 males (30.5%). The mean age of the participants was 71.2 years (SD = 12.6). For inner canal diameter patients were classified as: Type A (31/59, 53%), Type B (19/59, 32%), and Type C (9/59, 15%). For the Index Classification Group, patients were classified as: Group A (26/59, 44%), Group B (20/59, 34%), and Group C (13/59, 22%). There was no significant difference in overall revision rate between the three groups (χ2 = 3.25, P = .197 from a Chi-square test). There was a significantly higher rate of aseptic loosening in Group C compared to Groups A and B, with no significant difference between Groups A and B in terms of aseptic loosening rates (χ2 = 8.72, P = .013 from a Chi-square test).

CONCLUSIONS

Distal femoral morphology plays an important role in the risk of aseptic loosening following hinged knee replacement, and should be considered when deciding implant type and fixation in these patients.

Reliability of pre-resection ligament tension assessment in imageless robotic assisted total knee replacement

BACKGROUND

Ligament tension balance is a major determinant for the success of total knee replacement (TKR). The present study aimed at determining the inter-rater and intra-rater reliability in performing ligament tension assessment using an imageless robotic-assisted TKR.

METHODS

Twenty-four knees in 21 patients who received robotic-assisted TKR for end-stage varus osteoarthritis were examined. Three orthopedic specialists and six orthopedic trainees participated in the operations. Data from the ligament tension assessment were collected during the operations.

RESULTS

For the inter-rater reliability, "extension medial" and "flexion medial" had excellent reliability whilst "extension lateral" and "flexion lateral" had good-to-excellent reliability. For the intra-rater reliability, "extension medial" showed excellent reliability, "extension lateral" and "flexion medial" showed good-to-excellent reliability, and "flexion lateral" showed moderate-to-excellent reliability.

CONCLUSIONS

Robotic-assisted technology provides a reliable solution to improve ligament tension assessment. All ligament tension assessments with the use of the technology could demonstrate at least good-to-excellent reliability except for the intra-rater reliability of "flexion lateral".

Should All Patients Receive Extended Oral Antibiotic Prophylaxis? Defining Its Role in Patients Undergoing Primary and Aseptic Revision Total Joint Arthroplasty

BACKGROUND

Prior studies have demonstrated reduced periprosthetic joint infection (PJI) rates following extended oral antibiotics (EOAs) for high-risk patients undergoing primary total joint arthroplasty (TJA). This study compared 3-month PJI rates in all patients undergoing primary or aseptic revision TJA with or without EOA prophylaxis.

METHODS

In total, 2,982 consecutive primary (n = 2,677) and aseptic revision (n = 305) TJAs were performed by a single, fellowship-trained arthroplasty surgeon from 2016 to 2022 were retrospectively reviewed. Beginning January 2020, all patients received 7 days of 300 mg oral cefdinir twice daily immediately postoperatively. Rates of PJI at 3 months were compared between patients who received or did not receive EOA.

RESULTS

Rates of PJI at 3 months in patients undergoing primary and aseptic revision TJA were significantly lower in those receiving EOA prophylaxis compared to those who did not (0.41 versus 1.13%, respectively; P = .02). After primary TJA, lower PJI rates were observed with EOA prophylaxis utilization (0.23 versus 0.74%, P = .04; odds ratio [OR] 3.85). Following aseptic revision TJA, PJI rates trended toward a significant decrease with the EOA compared to without (1.88 versus 4.83%, respectively; P = .16; OR 2.71).

CONCLUSIONS

All patients undergoing primary or aseptic revision TJA who received EOA prophylaxis were 3.85 and 2.71 times less likely, respectively, to develop PJI at 3 months compared to those without EOA. Future studies are needed to determine if these results are maintained at postoperative time periods beyond 3 months following primary TJA.

LEVEL OF EVIDENCE

III, Retrospective review.

Early Versus Late Periprosthetic Joint Infection After Total Knee Arthroplasty: Do Patient Differences Exist?

BACKGROUND

Periprosthetic joint infection (PJI) is a devastating complication following total knee arthroplasty (TKA). Little evidence exists comparing those with early versus late PJI. The purpose of the study was to determine comorbidity profile differences between patients developing early and late PJI.

METHODS

There were 72,659 patients undergoing primary TKA from 2009 to 2021, who were identified from a commercial claims and encounters database. Subjects diagnosed with PJI were categorized as either 'early' (within 90 days of index procedure) or 'late' (> 2 years after index arthroplasty). Non-infected patients within these periods served as control groups following 4:1 propensity score matching on other extraneous variables. Logistic regression analyses were performed comparing comorbidities between groups.

RESULTS

Patients were significantly younger in the late compared to the early infection group (58.1 versus 62.4 years, P < .001). When compared to those with early PJI, patients who had chronic kidney disease (13.3 versus 4.1%; OR [odds ratio] 5.17, P = .002), malignancy (20.4 versus 10.5%; OR 2.53, P = .009), uncomplicated diabetes (40.8 versus 30.6%; OR 2.00, P = .01), rheumatoid arthritis (9.2 versus 3.3%; OR 2.66, P = .046), and hypertension (88.8 versus 81.6%; OR 2.17, P = .04), were all significant predictors of developing a late PJI.

CONCLUSIONS

When compared to patients diagnosed with early PJI following primary TKA, the presence of chronic kidney disease, malignancy, uncomplicated diabetes, rheumatoid arthritis, and hypertension, were independent risk factors for the development of late PJI. Younger patients who have these comorbidities may be targets for preoperative optimization interventions that minimize the risk of PJI.

Comparable bone penetration between antibiotic-loaded and plain bone cement in total knee arthroplasty

INTRODUCTION

One of the main concerns around the use of antibiotic-loaded bone cement (ALBC) is the potential reduction in the mechanical properties of the cement when antibiotics are admixed. The purpose of this study was to determine whether there is a difference between plain cement and ALBC in terms of radiological intrusion into the bone in total knee arthroplasties (TKAs).

METHODS

Prospective randomized study of 80 consecutive patients who underwent TKA. Depending on the cement used, patients were divided into two groups by a computer-generated randomization programme: the cement without antibiotic (Group 1) or the ALBC (Group 2). Cement intrusion was measured in postoperative radiographs in eight different regions in the tibial component and six regions in the femoral component.

RESULTS

The average cement intrusion was similar in both groups (p = nonsignificance [n.s.]). Group 1 (plain cement) had an average cement intrusion in the femur of 1.4 mm (±0.4) and 2.4 mm (±0.4) in the tibia. In Group 2 (ALBC), the average cement intrusion in the femur came to 1.6 (±0.5) and 2.4 mm (±0.5) in the tibia. In 80% of the patients, the cement intrusion in the tibia averaged a minimum of 2 mm, being similar in both groups (p = n.s.).

CONCLUSION

There are no differences in bone intrusion when comparing plain cement to ALBC. Therefore, the use of ALBC in primary TKA may be indicated, achieving optimal bone penetration.

LEVEL OF EVIDENCE

Level I.

Ultracongruent Versus Posterior-Stabilized Polyethylene: No Difference in Anterior Knee Pain but Decreased Noise Generation

BACKGROUND

Noise generation and anterior knee pain can occur after primary total knee arthroplasty (TKA) and may affect patient satisfaction. Polyethylene design in cruciate-sacrificing implants could be a variable influencing these complications. The purpose of this study was to analyze the effect of polyethylene design on noise generation and anterior knee pain.

METHODS

We prospectively reviewed a cohort of patients who underwent primary TKA between 2014 and 2022 by a single surgeon using either a posterior-stabilized (PS) or ultracongruent (UC) polyethylene of the same implant design. The primary outcomes were measured through a noise generation questionnaire and the Knee Injury and Osteoarthritis Outcome Score-Patellofemoral score.

RESULTS

A total of 409 TKA procedures were included, 153 (37.4%) PS and 256 (62.6%) UC. No difference was noted in the Knee Injury and Osteoarthritis Outcome Score-Patellofemoral score between PS and UC designs (71.7 ± 26 versus 74.2 ± 23.2, P = 0.313). A higher percentage of patients in the PS cohort reported hearing (32.7% versus 22.3%, P = 0.020) or feeling noise (28.8 versus 20.3, P = 0.051) coming from their implant. No notable difference was observed in noise-related satisfaction rates. Independent risk factors of noise generation were age (OR, 0.96; P = 0.006) and PS polyethylene (OR, 1.61; P = 0.043). Noise generation was associated with decreased patient-reported outcome measure scores (P < 0.001).

CONCLUSION

While there was no difference in anterior knee pain between PS and UC polyethylene designs, PS inserts exhibit higher rates of noise generation compared with UC. Noise generation had comparable satisfaction but was associated with decreased patient-reported outcome measure scores.

V-Y Quadricepsplasty for Knee Stiffness Post Total Knee Arthroplasty: A Case Report and Literature Review

Introduction

Knee stiffness post-total knee arthroplasty (TKA) represents a common and challenging complication. Standard treatment protocols primarily include physical therapy, manipulation under anesthesia (MUA), fibrotic tissue release, lysis of adhesions (LOA), and in refractory cases, revision arthroplasty. However, these interventions often show minimal improvement in refractory cases. This report introduces V-Y quadricepsplasty as an innovative approach for addressing knee stiffness post-TKA, particularly in cases unresponsive to MUA and LOA, without any evidence of prosthetic component malposition or failure.

Case Report

We present a case involving a middle-aged woman experiencing persistent knee stiffness post-TKA, unresponsive to both MUA and LOA. Diagnostic evaluations confirmed no malposition or failure of the prosthetic component. The patient underwent a successful V-Y quadricepsplasty, which resulted in significant improvement in her condition.

Conclusion

This case underscores the efficacy of V-Y quadricepsplasty in managing knee stiffness post-TKA, especially in cases where traditional treatments such as MUA and LOA are ineffective and there is no evidence of prosthetic component failure or malposition. This approach potentially offers a new avenue for treatment in similar clinical scenarios.

Phage therapy in prosthetic joint infections caused by Staphylococcus aureus - A literature review

Prosthetic joint infections (PJIs) are dreaded arthroplasty complications often caused by Staphylococcus aureus. Due to methicillin-resistant S. aureus (MRSA) strains or biofilm formation, successful treatment remains difficult. Currently, two-stage revision surgery constitutes the gold standard therapy of PJIs, sometimes replaced or supplemented by debridement, antibiotics, and implant retention (DAIR). Given the dire consequences of therapeutic failure, bacteriophage therapy might be another treatment option. Here we provide a comprehensive literature review addressing the efficacy of phages applied against S. aureus as causative agent of PJIs. The included 17 publications had in common that the applied phages proved to be effective against various S. aureus isolates including MRSA even in biofilms. Experiments with mice, rats, rabbits, and moth larvae confirmed favorable features of phage preparations in PJI treatment in vivo; including its synergistic with antibiotics. Case reports of PJI patients unanimously described the bacterial eradication following, alongside other measures, intravenous and intra-articular phage administration. Generally, no major side effects occurred, but in some cases elevated liver transaminases were observed. To conclude, our review compiled promising evidence suggesting the safety and suitability of phage therapy as an adjuvant to DAIR in S. aureus PJIs, and thus, underscores the significance of further research.

Clinical outcome and survival rate of condylar constrained knee prosthesis in revision total knee arthroplasty: an average nine point six year follow-up

PURPOSE

Condylar constrained knee prostheses (CCK) are increasingly used in revision total knee arthroplasty (rTKA), but the clinical effectiveness and long-term survival remain a debate. The purpose of this study is to report the long-term clinical and radiographic outcome, implant survival rate, and surgical safety of revision total knee arthroplasty with condylar constrained knee prosthesis.

METHODS

A retrospective cohort study was performed on patients undergoing rTKA with CCK. The cases who received rTKA with CCK from January 2005 to January 2022 were selected. The duration of operation, the estimated perioperative blood loss, and the intraoperative blood transfusion rate were recorded to evaluate surgical safety. The pain visual analog scale (VAS), range of motion (ROM), the Hospital for Special Surgery (HSS) score, the Knee Society Score (KSS), the Western Ontario and McMaster University Osteoarthritis Index (WOMAC), and the Oxford knee score (OKS) was recorded to assess clinical outcome. Standard anteroposterior, lateral, skyline and long-standing AP radiographs of the lower limbs were conducted to assess radiographic outcome. Implant survival was analyzed by Kaplan-Meier survival estimates.

RESULTS

Fifty-five cases were followed up for an average of 9.6 years (1-18 years), including 16 males and 38 females, with an average age of 66 and an average BMI of 26.9 kg/m2. The  main reasons for revision were periprosthetic infection (32 knees, 58.2%) and aseptic loosening (13 knees, 23.6%). The duration of operation was 149 ± 56.2 min. The perioperative blood loss was 973.6 ± 421.6 ml. At the last follow-up, VAS (8.0 ± 1.1 to 1.3 ± 1.4), ROM (82.7° ± 26.1° to 108.4° ± 11.8°), HSS (45.0 ± 10.4 to 85.3 ± 8.6), KSKS (38.4 ± 12.1 to 88.5 ± 12.0), KSFS (19.6 ± 12.9 to 68.8 ± 15.1), WOMAC (67.9 ± 12.5 to 14.4 ± 9.5), and OKS (9.9 ± 4.2 to 41.6 ± 7.7) were significantly improved (P < 0.001). A total of five complications were observed, all of which were periprosthetic infection. Non-progressive radiolucent lines were observed in 26 knees (47.3%). The 10-year survival rate for no operation was 96.0%. The ten year survival rate for no revision was 98.0%.

CONCLUSION

The use of CCK prosthesis for rTKA can achieve good long-term efficacy and prosthesis survival.

Distal femoral replacement for the treatment of periprosthetic distal femoral fractures around a total knee arthroplasty: a meta-analysis

Background

Periprosthetic fracture is a rare complication of arthroplasty but can have devastating consequences for the patient and presents a complex surgical challenge. Locking compression plate and retrograde intramedullary nail are both widely accepted surgical fixation techniques for distal femoral periprosthetic fractures around a total knee arthroplasty. Although there is still a need for further high-quality research into both techniques, there is even less literature concerning the use of distal femoral replacement to treat distal femoral periprosthetic fractures. Interest has been piqued in distal femoral replacements for the treatment of distal femoral periprosthetic fractures due to the theoretical advantages of immediate post-operative weight-bearing and lack of dependence on fracture union, but there are still understandably reservations about performing such an extensive and invasive procedure when an accepted alternative is available. This meta-analysis aims to evaluate the current literature to compare the complication rates and return to pre-operative ambulatory status of distal femoral replacement and locking compression plate.

Method

A literature search was performed to identify articles related to the management of distal femoral periprosthetic fractures around a total knee arthroplasty in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. Methodological quality was assessed using the methodological index for non-randomized studies (MINORS) criteria. Articles were reviewed, and data extracted for analysis.

Results

Five articles met the inclusion criteria, reporting on 345 periprosthetic fractures. The overall rates of complications for distal femoral replacement and locking compression plate were: re-operation (6.1% vs 12.1%), infection (3.0% vs 5.3%), mortality (19.7% vs 19.3%), and return to pre-operative ambulatory status (60.9% vs 71.8%) (respectively).

Conclusion

This meta-analysis shows no statistically significant difference in the rates of re-operation, infection, mortality or return to pre-operative ambulatory status when comparing distal femoral replacement to locking compression plate.

Use of semi-constrained total knee arthroplasty in gonarthrosis with collateral ligament insufficiency: Clinical and functional outcomes

INTRODUCTION

Achieving stability in total knee arthroplasty (TKA) is crucial for long-term implant survival. In cases of severe deformity or ligament laxity, constrained implants may be required. Traditionally, increasing constraint involved intramedullary stems. However, there are intermediary alternatives, including employing a constrained polyethylene insert without stems, thereby avoiding complications related to them. The study aims to evaluate our experience with a non-modular constrained (NMC) implant in primary TKA.

MATERIAL AND METHODS

We conducted a retrospective review of the clinical and radiographic outcomes of 108 non-stemmed primary TKAs performed at our institution between 2013 and 2021 in patients with at least 10° deformity or 10mm ligament laxity. Data included demographics, preoperative and postoperative deformities, clinical outcomes and revision rates.

RESULTS

A total of 103 patients (108 knees) with a mean age of 74 were followed up for a minimum of 2 years. The mean postoperative range of motion was 105°/0°. The median Oxford Knee Score, Knee Society Score and Knee Society Function Score were 43.5, 92 and 90, respectively. 17 knees had varus deformity (mean tibiofemoral angle of 2.7°), and 87 knees had excessive valgus deformity (mean tibiofemoral angle of 15.1°). The remaining 4 knees had a neutral alignment. The mean postoperative tibiofemoral angle was 6.8°. The overall revision rate was 6.5% (7 patients): 3 deep periprosthetic infections, 2 patellar dislocations, 1 stiffness and 1 aseptic loosening.

CONCLUSION

Our experience demonstrates favorable mid-term outcomes with the NMC implant, providing a safe alternative to stemmed implants in primary TKA, particularly in cases of severe deformity or ligament laxity.

Shoulder Adhesive Capsulitis Prior to Total Knee Arthroplasty is Associated With Increased Rates of Postoperative Stiffness Requiring Manipulation Under Anesthesia and Arthroscopic Lysis of Adhesions

BACKGROUND

Arthrofibrosis following total knee arthroplasty (TKA) and adhesive capsulitis (AC) of the shoulder develop via a similar pathologic process. The purpose of this study was to examine the relationship between these two conditions.

METHODS

This was a retrospective cohort study using a large nationwide claims database. Patients who had a history of shoulder AC prior to TKA were compared to TKA patients who did not have AC history comparing rates of postoperative stiffness, manipulation under anesthesia (MUA), arthroscopic lysis of adhesions (LOAs), and revision arthroplasty at postoperative timepoints (3 months, 6 months, 1 year, and 2 years).

RESULTS

Within 3 months, 6 months, 1 year, and 2 years of their TKAs, patients who had a history of AC prior to TKA were significantly more likely to experience stiffness (OR [odds ratio] = 1.29, 1.28, 1.32, and 1.36, respectively) and LOAs (OR = 6.78, 3.65, 2.99, and 2.81, respectively). They also showed increased risk of MUA within 6 months, 1 year, and 2 years (OR = 1.15, 1.15, and 1.16, respectively) of their TKAs. Patients having a preoperative diagnosis of AC did not have an increased risk of undergoing revision surgery 1 year or 2 years after their TKAs (P > .05).

CONCLUSIONS

Patients diagnosed with AC prior to TKA experience higher rates of postoperative stiffness, resulting in additional interventions such as MUA and LOAs. These findings identify a particularly high-risk patient population that may benefit from additional interventions prior to and following TKA.

LEVEL OF EVIDENCE

This is a level III prognostic study.

Failure of the Yoke With a Rotating-Hinge Total Knee Arthroplasty: A Case Report

CASE

A patient underwent revision of a total knee replacement to a cementless rotating-hinge prosthesis. The femoral component became loose, but due to the patient's frailty and cognitive decline, revision was not performed. Subsequently, the yoke failed, dissociating the femoral and tibial components, necessitating a single-stage revision.

CONCLUSION

This case underlines the need for robust fixation of components of rotating-hinge knee replacements to avoid mechanical failures. It contributes valuable insights to the limited literature on yoke failure in total knee arthroplasty, emphasizing the importance of implant design, patient selection, and surgical technique to prevent such complications.

AdipoRon reduces TGFβ1-mediated collagen deposition in vitro and alleviates knee stiffness in vivo

Arthrofibrosis, which causes joint motion restrictions, is a common complication following total knee arthroplasty (TKA). Key features associated with arthrofibrosis include myofibroblast activation, knee stiffness, and excessive scar tissue formation. We previously demonstrated that adiponectin levels are suppressed within the knee tissues of patients affected by arthrofibrosis and showed that AdipoRon, an adiponectin receptor agonist, exhibited anti-fibrotic properties in human mesenchymal stem cells. In this study, the therapeutic potential of AdipoRon was evaluated on TGFβ1-mediated myofibroblast differentiation of primary human knee fibroblasts and in a mouse model of knee stiffness. Picrosirius red staining revealed that AdipoRon reduced TGFβ1-induced collagen deposition in primary knee fibroblasts derived from patients undergoing primary TKA and revision TKA for arthrofibrosis. AdipoRon also reduced mRNA and protein levels of ACTA2, a key myofibroblast marker. RNA-seq analysis corroborated the anti-myofibrogenic effects of AdipoRon. In our knee stiffness mouse model, 6 weeks of knee immobilization, to induce a knee contracture, in conjunction with daily vehicle (DMSO) or AdipoRon (1, 5, and 25 mg/kg) via intraperitoneal injections were well tolerated based on animal behavior and weight measurements. Biomechanical testing demonstrated that passive extension angles (PEAs) of experimental knees were similar between vehicle and AdipoRon treatment groups in mice evaluated immediately following immobilization. Interestingly, relative to vehicle-treated mice, 5 mg/kg AdipoRon therapy improved the PEA of the experimental knees in mice that underwent 4 weeks of knee remobilization following the immobilization and therapy. Together, these studies revealed that AdipoRon may be an effective therapeutic modality for arthrofibrosis.

Global mapping of institutional and hospital-based (Level II-IV) arthroplasty registries: a scoping review

PURPOSE

Four joint arthroplasty registries (JARs) levels exist based on the recorded data type. Level I JARs are national registries that record primary data. Hospital or institutional JARs (Level II-IV) document further data (patient-reported outcomes, demographic, radiographic). A worldwide list of Level II-IV JARs must be created to effectively assess and categorize these data.

METHODS

Our study is a systematic scoping review that followed the PRISMA guidelines and included 648 studies. Based on their publications, the study aimed to map the existing Level II-IV JARs worldwide. The secondary aim was to record their lifetime, publications' number and frequency and recognise differences with national JARs.

RESULTS

One hundred five Level II-IV JARs were identified. Forty-eight hospital-based, 45 institutional, and 12 regional JARs. Fifty JARs were found in America, 39 in Europe, nine in Asia, six in Oceania and one in Africa. They have published 485 cohorts, 91 case-series, 49 case-control, nine cross-sectional studies, eight registry protocols and six randomized trials. Most cohort studies were retrospective. Twenty-three per cent of papers studied patient-reported outcomes, 21.45% surgical complications, 13.73% postoperative clinical and 5.25% radiographic outcomes, and 11.88% were survival analyses. Forty-four JARs have published only one paper. Level I JARs primarily publish implant revision risk annual reports, while Level IV JARs collect comprehensive data to conduct retrospective cohort studies.

CONCLUSIONS

This is the first study mapping all Level II-IV JARs worldwide. Most JARs are found in Europe and America, reporting on retrospective cohorts, but only a few report on studies systematically.

Periprosthetic Distal Femoral Fractures Around a Total Knee Arthroplasty: a Meta-analysis Comparing Locking compression Plating and Retrograde Intramedullary Nailing

Purpose

The number of total knee replacements (TKRs) performed per year has been increasing annually and it is estimated that by 2030 demand would reach 3.48 million procedures per year in the United States Of America. The prevalence of periprosthetic fractures (PPFs) around TKRs has followed this trend with incidences ranging from 0.3% to 3.5%. Distal femoral PPFs are associated with significant morbidity and mortality. When there is sufficient bone stock in the distal femur and a fracture pattern conducive to fixation, locking compression plating (LCP) and retrograde intramedullary nailing (RIMN) are commonly used fixation strategies. Conversely, in situations with loosening and deficient bone stock, a salvage procedure such as a distal femoral replacement is recognized as an alternative. This meta-analysis investigates the rates of non-union, re-operation, infection, and mortality for LCPs and RIMNs when performed for distal femoral PPFs fractures around TKRs.

Method

A search was conducted to identify articles relevant to the management of distal femoral PPFs around TKRs in adherence to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist. Articles meeting the inclusion criteria were then assessed for methodological quality using the methodological items for non-randomised studies (MINORS) criteria. Articles were reviewed, and data were compiled into tables for analysis.

Results

10 articles met the inclusion criteria, reporting on 528 PPFs. The overall incidence of complications was: non-union 9.4%, re-operation 12.9%, infection 2.4%, and mortality 5.5%. This meta-analysis found no significant differences between RIMN and LCP in rates of non-union (9.2% vs 9.6%) re-operation (15.1% vs 11.3%), infection (2.1% vs 2.6%), and mortality (6.0% vs 5.2%), respectively.

Conclusion

This meta-analysis demonstrated no significant difference in rates of non-union, re-operation, infection, and mortality between RIMN and LCP and both remain valid surgical treatment options.

Computational screening of biomarkers and potential drugs for arthrofibrosis based on combination of sequencing and large nature language model

Background

Arthrofibrosis (AF) is a fibrotic joint disease resulting from excessive collagen production and fibrous scar formation after total knee arthroplasty (TKA). This devastating complication may cause consistent pain and dramatically reduction of functionality. Unfortunately, the conservative treatments to prevent the AF in the early stage are largely unknown due to the lack of specific biomarkers and reliable therapeutic targets.

Methods

In this study, we extracted1782 fibrosis related genes (FRGs) from 373,461published literature based on the large natural language processing models (ChatGPT) and intersected with the 2750 differential expressed genes (DEGs) from mRNA microarray (GSE135854). A total of 311 potential AF biomarker genes (PABGs) were obtained and functional analysis were performed including gene ontology (GO) annotation and the Kyoto Encyclopedia of Genes and Genomes (KEGG) pathway enrichment analyses. Subsequently, we accomplished validation in AF animal models with immobilization of the unilateral knee joints of 16 rabbits for 1-week, 2-weeks, 3-weeks and 4-weeks. Finally, we tested the biomarkers in a retrospective cohort enrolled 35 AF patients and 35 control group patients.

Results

We identified G-protein-coupled receptor 17 (GPR17) as a reliable therapeutic biomarker for AF diagnosis with higher AUC (0.819) in the ROC curve. A total of 21 potential drugs targeted to GPR17 were screened. Among them, pranlukast and montelukast have achieved therapeutic effect in animal models. In addition, we established an online AF database for data integration (https://chenxi2023.shinyapps.io/afdbv1).

Conclusions

These results unveiling therapeutic biomarkers for AF diagnosis, and provide potential drugs for clinical treatment.

The translational potential of this article

Our study demonstrated that GPR17 holds significant promise as a potential biomarker and therapeutic target for arthrofibrosis. Moreover, pranlukast and montelukast targeted to GPR17 that could be instrumental in the treatment of AF.

Radiolucent line assessment in cemented stemmed total knee (RISK) arthroplasty: validation of a modernized classification system

BACKGROUND

This study aims to implement and assess the inter- and intra-reliability of a modernized radiolucency assessment system; the Radiolucency In cemented Stemmed Knee (RISK) arthroplasty classification. Furthermore, we assessed the distribution of regions affected by radiolucency in patients undergoing stemmed cemented total knee arthroplasty.

METHODS

Stemmed total knee arthroplasty cases over 7-year period at a single institution were retrospectively identified and reviewed. The RISK classification system identifies five zones in the femur and five zones in the tibia in both the anteroposterior (AP) and lateral planes. Post-operative and follow-up radiographs were scored for radiolucency by four blinded reviewers at two distinct time points four weeks apart. Reliability was assessed using the kappa statistic. A heat map was generated to demonstrate the reported regions of radiolucency.

RESULTS

29 cases (63 radiographs) of stemmed total knee arthroplasty were examined radiographically using the RISK classification system. Intra-reliability (0.83) and Inter-reliability (0.80) scores were both consistent with a strong level of agreement using the kappa scoring system. Radiolucency was more commonly associated with the tibial component (76.6%) compared to the femoral component (23.3%), and the tibial anterior-posterior (AP) region 1 (medial plateau) was the most affected (14.9%).

CONCLUSION

The RISK classification system is a reliable assessment tool for evaluating radiolucency around stemmed total knee arthroplasty using defined zones on both AP and lateral radiographs. Zones of radiolucency identified in this study may be relevant to implant survival and corresponded well with zones of fixation, which may help inform future research.

Comparing machine learning algorithms for non-invasive detection and classification of failure in piezoresistive bone cement via electrical impedance tomography

At an estimated cost of $8 billion annually in the United States, revision surgeries to total joint replacements represent a substantial financial burden to the health care system and a tremendous mental and physical burden on patients and their caretakers. Fixation failures, such as implant loosening, wear, and mechanical instability of the poly(methyl methacrylate) (PMMA) cement, which bonds the implant to the bone, are the main causes of long-term implant failure. Early and accurate diagnosis of cement failure is critical for developing novel therapeutic strategies and reducing the high risk of a misjudged revision. Unfortunately, prevailing imaging modalities, notably plain radiographs, struggle to detect the precursors of implant failure and are often interpreted incorrectly. Our prior work has shown that the modification of PMMA bone cement with low concentrations of conductive fillers makes it piezoresistive and therefore self-sensing. When combined with a conductivity imaging modality such as electrical impedance tomography (EIT), it is possible to monitor load transfer across the PMMA using cost-effective, physiologically benign, non-contact, and real-time electrical measurements. Despite the ability of EIT for monitoring load transfer across self-sensing PMMA bone cement, it is unable to accurately characterize failure mechanisms. Overcoming this challenge is critical to the success of this technology in practice. Therefore, we herein expand upon our previous results by integrating machine learning techniques with EIT for cement condition characterization with the goal of establishing the feasibility of even off-the-shelf machine learning algorithms to address this important problem. We survey a wide variety of different machine learning algorithms for application to this problem, including neural networks on voltage readings of an EIT phantom for tracking the spatial position of a sample, specifying defect orientation within a sample, and classifying defect types, including cracks and delaminations. In addition, we explore the utilization of principal component analysis (PCA) for pre-treating impedance signals in each of these problems. Within the tested algorithms, our results show clear advantages of neural networks, support vector machines, and K-nearest neighbor algorithms for interpreting EIT signals. We also show that PCA is an effective addition to machine learning. These preliminary results demonstrate that the combination of smart materials, EIT, and machine learning may be a powerful instrumentation tool for diagnosing the origin and evolution of mechanical failure in joint replacements.

Arthrofibrosis After Total Knee Arthroplasty: A Critical Analysis Review

» Arthrofibrosis after total knee arthroplasty (TKA) is the new formation of excessive scar tissue that results in limited ROM, pain, and functional deficits.» The diagnosis of arthrofibrosis is based on the patient's history, clinical examination, absence of alternative diagnoses from diagnostic testing, and operative findings. Imaging is helpful in ruling out specific causes of stiffness after TKA. A biopsy is not indicated, and no biomarkers of arthrofibrosis exist.» Arthrofibrosis pathophysiology is multifactorial and related to aberrant activation and proliferation of myofibroblasts that primarily deposit type I collagen in response to a proinflammatory environment. Transforming growth factor-beta signaling is the best established pathway involved in arthrofibrosis after TKA.» Management includes both nonoperative and operative modalities. Physical therapy is most used while revision arthroplasty is typically reserved as a last resort. Additional investigation into specific pathophysiologic mechanisms can better inform targeted therapeutics.

The Practice Patterns of American Association of Hip and Knee Surgeons for the Management of Chronic Periprosthetic Joint Infection After Total Knee Arthroplasty

BACKGROUND

The management of periprosthetic joint infection (PJI) following total knee arthroplasty (TKA) has considerable variation. In order to better capture current preferences for the management of PJI, this study sought to poll the current members of American Association of Hip and Knee Surgeons (AAHKS) first to characterize the distribution of practice patterns.

METHODS

There were 32 questions in an online survey distributed to members of AAHKS. The questions were multiple choice regarding the management of PJI for TKA. There were 844 out of 2,752 members who completed the survey (response rate of 31%).

RESULTS

Most of the members were in private practice (50%) compared to 28% being in an academic setting. On average, members were performing between 6 to 20 PJI cases per year. Two-stage exchange arthroplasty was performed in over 75% of the cases with either a cruciate retaining (CR) or posterior stabilized (PS) primary femoral component used in over 50% of the cases and 62% using an all-polyethylene tibial implant. Most of the members were using vancomycin and tobramycin. Typically, 2 to 3 grams of antibiotics were added per bag of cement regardless of the cement type. When indicated, amphotericin was the most often-used antifungal. Post-operative management had major variability with range of motion, brace use, and weight-bearing restrictions.

CONCLUSION

There was variability in the responses from the members of AAHKS, but there was a preference toward performing a two-stage exchange arthroplasty with an articulating spacer using a metal femoral component and an all-polyethylene liner.

Robotic-assisted mechanically aligned total knee arthroplasty does not lead to better clinical and radiological outcomes when compared to conventional TKA: a systematic review and meta-analysis of randomized controlled trials

PURPOSE

Robotic-assisted total knee arthroplasty (R-TKA) has emerged as an alternative to improve the results of the conventional manual TKA (C-TKA). The aim of this study was to analyse the high-level studies comparing R-TKA and C-TKA in terms of clinical outcomes, radiological results, perioperative parameters, and complications.

METHODS

The literature search was conducted on three databases (PubMed, Cochrane, and Web of Science) on 1 February 2023 according to the guidelines for Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). Inclusion criteria were: randomized controlled trials (RCTs), written in English language, published in the last 15 years, focusing on the comparison of C-TKA and R-TKA results. The quality of each article was assessed using the Cochrane risk-of-bias tool for randomized trials version 2 (RoB 2). The statistical analysis was carried out using random effects (DerSimonian & Laird) for weighted mean difference (MD) of the continuous variables and Peto method for odds ratios of the dichotomous variables.

RESULTS

Among the 2905 articles retrieved, 14 RCTs on 12 series of patients treated with mechanically aligned implants were included. A total of 2255 patients (25.1% males and 74.9% females; mean age 62.9 ± 3.0; mean BMI 28.1 ± 1.3) were analysed. The results of this systematic review and meta-analysis showed that R-TKA did not provide overall superior results compared to C-TKA in mechanically aligned implants in terms of clinical and radiological outcomes. R-TKA showed longer operative time (MD = 15.3 min, p = 0.004) and similar complication rates compared to C-TKA. A statistically significant difference in favour of R-TKA was found in the posterior-stabilized subgroup in terms of radiological outcomes (hip-knee-ankle angle MD = 1.7, p < 0.001) compared to C-TKA, although without resulting in appreciable difference of clinical outcomes.

CONCLUSION

R-TKA did not provide overall superior results compared to C-TKA in terms of clinical and radiological outcomes, showing longer operative time and similar complication rates.

LEVEL OF EVIDENCE

Level I.

Does interaction occur between risk factors for revision total knee arthroplasty?

INTRODUCTION

Several risk factors for revision TKA have previously been identified, but interactions between risk factors may occur and affect risk of revision. To our knowledge, such interactions have not been previously studied. As patients often exhibit multiple risk factors for revision, knowledge of these interactions can help improve risk stratification and patient education prior to TKA.

MATERIALS AND METHODS

The State Inpatient Databases (SID), part of the Healthcare Cost and Utilization Project (HCUP), were queried to identify patients who underwent TKA between January 1, 2006 and December 31, 2015. Risk factors for revision TKA were identified, and interactions between indication for TKA and other risk factors were analyzed.

RESULTS

Of 958,944 patients who underwent TKA, 33,550 (3.5%) underwent revision. Age, sex, race, length of stay, Elixhauser readmission score, urban/rural designation, and indication for TKA were significantly associated with revision (p < 0.05). Age was the strongest predictor (p  < 0.0001), with younger patients exhibiting higher revision risk. Risks associated with age were modified by an interaction with indication for TKA (p < 0.0001). There was no significant interaction between sex and indication for TKA (p = 0.535) or race and indication for TKA (p = 0.187).

CONCLUSIONS

Age, sex, race, length of stay, Elixhauser readmission score, urban/rural designation, and indication for TKA are significantly associated with revision TKA. Interaction occurs between age and indication.

Single-cell and bulk tissue sequencing unravels the heterogeneity of synovial microenvironment in arthrofibrosis

Arthrofibrosis (AF) is a debilitating complication that occurs after trauma or surgery, leading to functional impairment and surgical failures worldwide. This study aimed to uncover the underlying mechanism of AF. A total of 141 patients were enrolled, and synovial samples were collected from both patients and animal models at different time points. Single-cell RNA-sequencing (scRNA-seq) and bulk tissue RNA sequencing (bulk-seq) were employed to profile the distinct synovial microenvironment. This study revealed changes in cell proportions during AF pathogenesis and identified Engrailed-1 (EN1) as a key transcription factor strongly associated with disease severity and clinical prognosis. Additionally, the researchers discovered a specific type of synovial fibroblast called DKK3-SLF, which played a critical role in driving AF development. These findings shed light on the composition and heterogeneity of the synovial microenvironment in AF, offering potential avenues for identifying therapeutic targets and developing clinical treatments for AF and other fibrotic diseases.

Mapping the course to recovery: a prospective study on the anatomic distribution of early postoperative pain after total knee arthroplasty

INTRODUCTION

Early postoperative pain following total knee arthroplasty significantly impacts outcomes and patient satisfaction. However, the characteristics and sources of early pain after total knee arthroplasty remain unclear. Therefore, the purpose of this study was to determine the anatomic distribution and course of postoperative pain in the acute and subacute period following total knee arthroplasty.

METHODS

A prospective observational study of primary, elective unilateral total knee arthroplasty cases was conducted at our academic tertiary care medical center from January 2021 to September 2021. Preoperative variables were extracted from institutional electronic medical records. Postoperatively, patients utilized a knee pain map to identify the two locations with the most significant pain and rated it using the visual analog scale (VAS). The data were collected on day 0, at 2 weeks, 2 months, and 6 months after operation.

RESULTS

This study included 112 patients, with 6% of patients having no pain at postoperative day 0, 22% at 2 weeks, 46% at 2 months, and 86% at 6 months after operation. In those who reported pain, the VAS score (mean ± standard deviation) was 5.8 ± 2.4 on postoperative day 0 and decreased at each follow-up time point (5.4 ± 2.3 at 2 weeks, 3.9 ± 2.2 at 2 months, and 3.8 ± 2.7 at 6 months). The majority of patients were able to identify distinct loci of pain. The most common early pain loci were patellae, thigh, and medial joint line, and this distribution dissipated by 6 months.

CONCLUSION

At 2 postoperative weeks, pain was primarily at the medial joint, and at 6 months postoperatively, pain was more likely to be at the lateral joint. No relationship was found between pain at six months and pain scores or location at postoperative day 0 or 2 weeks. Understanding the distribution and progression of knee pain following total knee arthroplasty may benefit patient education and targeted interventions.

LEVEL OF EVIDENCE

Level II, prospective observational study.

Clinical Trials with Mesenchymal Stem Cell Therapies for Osteoarthritis: Challenges in the Regeneration of Articular Cartilage

Osteoarthritis (OA) is a whole-joint disease primarily characterized by the deterioration of hyaline cartilage. Current treatments include microfracture and chondrocyte implantation as early surgical strategies that can be combined with scaffolds to repair osteochondral lesions; however, intra-articular (IA) injections or implantations of mesenchymal stem cells (MSCs) are new approaches that have presented encouraging therapeutic results in animal models and humans. We critically reviewed clinical trials with MSC therapies for OA, focusing on their effectiveness, quality, and outcomes in the regeneration of articular cartilage. Several sources of autologous or allogeneic MSCs were used in the clinical trials. Minor adverse events were generally reported, indicating that IA applications of MSCs are potentially safe. The evaluation of articular cartilage regeneration in human clinical trials is challenging, particularly in the inflammatory environment of osteoarthritic joints. Our findings indicate that IA injections of MSCs are efficacious in the treatment of OA and the regeneration of cartilage, but that they may be insufficient for the full repair of articular cartilage defects. The possible interference of clinical and quality variables in the outcomes suggests that robust clinical trials are still necessary for generating reliable evidence with which to support these treatments. We suggest that the administration of just-sufficient doses of viable cells in appropriate regimens is critical to achieve effective and durable effects. In terms of future perspectives, genetic modification, complex products with extracellular vesicles derived from MSCs, cell encapsulation in hydrogels, and 3D bioprinted tissue engineering are promising approaches with which to improve MSC therapies for OA.

Patient-specific instrumentation in total knee arthroplasty: a review of the current literature

Total knee arthroplasty (TKA) is one of the most frequently performed interventions in the field of Orthopaedic surgery. Over the last decades the implantation technique has improved continuously. The majority of patients is satisfied with the clinical outcome of TKA. However in various clinical follow-ups, up to 20% of unsatisfied patients can be observed. Periprosthetic infection and aseptic loosening seem to be the most common reasons for failure. Malalignment has been discussed as a cause of aseptic loosening and often leads to revision surgery. In order to increase the precision of implant positioning and alignment, new technologies such as patient-specific instrumentation (PSI) have been developed. Since the introduction of PSI, multiple clinical studies have been performed analyzing the clinical and radiological outcome of TKA with PSI technique. This review covers the recent literature of PSI in respect to surgical accuracy, clinical outcome, time- and cost-effectiveness.

The Role of Constraint in Revision Total Knee Replacement for Instability: Full Component Revision Vs Isolated Polyethylene Exchange in Selected Patients

Background

Instability is a common indication for revision after total knee arthroplasty. Replacement of multiple components is the current standard, but isolated polyethylene liner exchange (IPE) may present a less-morbid alternative. This study aims to determine (1) whether IPE results in similar rerevision frequency to component revision in select patients with symptomatic instability and (2) the effect of increasing constraint on the outcome.

Methods

We retrospectively reviewed 117 patients revised for symptomatic total knee arthroplasty instability from January 2016 to December 2017. The component revision (60 patients) or IPE (57 patients) cohorts were further stratified based on whether constraint was increased or not. The primary objective was to compare rerevision rates 2 years after component revision vs IPE. The secondary objectives consisted of evaluating reasons for rerevision, preoperative and postoperative patient-reported outcome measures, and range of motion.

Results

The rerevision rate was 18%, with no statistical difference between component and IPE cohorts. Cases where level of constraint increased due to revision, a significantly lower rate of rerevision was detected (9 of 77) (12%) than in cases where constraint did not increase (12 of 39) (31%) (P=0.012). This association was also noted in the component revision cohort but not in the IPE cohort (P=0.011).

Conclusions

Rerevision occurred at similar frequencies 2 years after IPE or component revision for total knee arthroplasty instability. For component revision, increased constraint was associated with significantly fewer rerevisions.

Physical activity after revision knee arthroplasty including return to sport and work: a systematic review and meta-analysis including GRADE

BACKGROUND

The number of primary knee arthroplasties (KAs) performed annually is rising, especially among active, working age patients. Consequently, revision KA is also increasingly performed. Our aim was to systematically review the extent to which patients were physically active following revision KA, and the rate and timing of return to sport and work.

METHODS

A search was conducted in the databases Medline and Embase until February 24th, 2023. Studies describing patients with revision total knee arthroplasty (rTKA) or revision unicondylar knee arthroplasty (rUKA), with outcomes regarding physical activity or return to sport (RTS) or work (RTW) were included. Quality of studies was assessed using the Newcastle-Ottawa scale, meta-analyses were performed using RevMan 5.4 and Grading of Recommendations, Assessment, Development, and Evaluations (GRADE).

RESULTS

Of the 4,314 articles screened, 22 studies were included describing 2,462 rTKA patients (no rUKA), 42% were male with a mean age of 67 years (range 24 - 95). No studies reported objective physical activity measurements. Twenty-two studies reported patient reported outcome measures (PROMs). The PROMs that were pooled on a scale from zero to ten were the UCLA Activity Score, the Tegner Activity Level Scale, the Lower-Extremity Activity Scale, Devane Activity Score, and physical activity related subscales of the Knee injury and Osteoarthritis Outcome Score. The retrospective studies of moderate quality showed a statistically significant postoperative improvement of 1.7 points (MD = 1.71, 95% CI 1.48 - 1.94 (p < 0.0001); 14 studies, n = 1,211). For the prospective moderate-quality studies, a statistically significant postoperative increase of 0.9 points was found (MD = 0.89, 95% CI 0.48 - 1.30 (p < 0.0001); 6 studies, n = 1,027). Regarding RTS, 12% of patients participated in so-called 'non-recommended' activities (i.e., hockey, soccer, football, gymnastics, jogging, singles tennis, and basketball) after rTKA (1 study, n = 206). The pooled RTW was 86% (2 studies, range 18-95%, n = 234).

CONCLUSIONS

The majority of patients self-reported an improved postoperative activity level after rTKA. Patients could maintain an active lifestyle in daily life, including sports and work. For reliable physical activity, RTS and RTW estimations, more studies are required. In terms of GRADE, the quality of evidence for the five prospective studies was rated as low.

LEVEL OF EVIDENCE

Level 3.

Periprosthetic distal femur fractures around total knee replacements: A comprehensive review

With a growing number of patients undergoing total knee replacements globally, coupled with an elderly population, the incidence of periprosthetic fractures around total knee replacements is increasing. As such, this is a highly topical subject that is gaining increasing interest within the orthopaedic community. This review provides a narrative synthesis of the most contemporary literature regarding distal femoral periprosthetic fractures. We review the related epidemiology, initial patient evaluation, the evolution and relevance of the classification systems and treatment options, particularly related to endoprosthetics and hybrid fixation constructs. The latest orthopaedic evidence related to this topic has been included.

Medial Varus Proximal Tibial Resection is Superior to Pie-Crusting of the Medial Collateral Ligament During Primary Total Knee Arthroplasty

BACKGROUND

Medial varus proximal tibial (MPT) resection or soft tissue releases (STR) of the medial collateral ligament (MCL) in form of pie-crusting can be performed to achieve a balanced knee in a varus deformity. Studies comparing the two modalities have not been addressed within the literature. Therefore, the aims of this study were to assess: 1) compartmental changes between the two methods; and 2) changes in patient-reported outcome measurements (PROMs).

METHODS

Using our institution's total joint arthroplasty registry, patients who underwent primary total knee arthroplasty from January 1, 2017 to December 31, 2019 were identified. The MPT resection and STR patients were 1:1 matched with baseline parameters yielding 196 patients. Outcomes of interest included: changes in compartmental pressures at 10, 45, and 90° degrees and change to the Short-Form 12 (SF-12), Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC), and Forgotten Joint Scores (FJS) at the two-year follow-up period. A P-value less than 0.05 was used as our threshold for statistical difference.

RESULTS

The MPT resection led to significant reductions in compartmental pressures at 10° [43 vs 19 pounds (lbs.), P<0.0001), 45° (43 vs 27 lbs., P<0.0001), and 90° degrees (27 vs. 16 lbs., P<0.0001) compared to STR. MPT resection also had significantly improved SF-12 (47 vs. 38, P<0.0001), WOMAC (9 vs. 21, P<0.0001), and FJS (79 vs. 68, P=0.005).

CONCLUSION

Bone modification was superior to pie-crusting of the MCL in achieving consistent pressure balancing and improved outcomes. The investigation can guide surgeons on the preferred method to achieve a well-balanced knee.

Mid-term survivorship of primary total knee arthroplasty with a specific implant

The purpose of this study was to assess mid-term survivorship following primary total knee arthroplasty (TKA) with Optetrak Logic components and identify the most common revision indications at a single institution. We identified a retrospective cohort of 7,941 Optetrak primary TKAs performed from January 2010 to December 2018. We reviewed the intraoperative findings of 369 TKAs that required revision TKA from January 2010 to December 2021 and the details of the revision implants used. Kaplan-Meier analysis was used to determine survivorship. Cox regression analysis was used to examine the impact of patient variables and year of implantation on survival time. The estimated survivorship free of all-cause revision was 98% (95% confidence interval (CI) 97% to 98%), 95% (95% CI 95% to 96%), and 86% (95% CI 83% to 88%) at two, five, and ten years, respectively. In 209/369 revisions there was a consistent constellation of findings with varying severity that included polyethylene wear and associated synovitis, osteolysis, and component loosening. This failure mode, which we refer to as aseptic mechanical failure, was the most common revision indication. The mean time from primary TKA to revision for aseptic mechanical failure was five years (5 months to 11 years). In this series of nearly 8,000 primary TKAs performed with a specific implant, we identified a lower-than-expected mid-term survivorship and a high number of revisions with a unique presentation. This study, along with the recent recall of the implant, confirms the need for frequent monitoring of patients with Optetrak TKAs given the incidence of polyethylene failure, osteolysis, and component loosening.

Stability analysis of tranexamic acid in the presence of various antiseptic solutions

Tranexamic acid (TXA) effectively reduces blood loss and transfusion risk during total joint arthroplasty. Additionally, intraoperative irrigation with various antiseptic solutions is often utilized for the management and prevention of surgical site infection. However, interactions between various antiseptic solutions and TXA have not been investigated. The purpose of this in vitro study is to evaluate the stability of TXA in the presence of common orthopedic antiseptic solutions. Five antiseptic solutions-0.1% chlorhexidine (CHX) gluconate, 10% povidone-iodine (BTD), 0.5% sodium hypochlorite (Dakin's), 3% hydrogen peroxide (H₂ O₂ ), and 1.5% H₂ O₂ -and a 0.9% normal saline (NS) control were obtained. A stock 100 mg/ml TXA solution was diluted in each antiseptic solution to a concentration of 10.0 mg/ml to generate reference standard and stability samples. TXA stability in each solution was measured using high performance liquid chromatography at t = 0 and t = 120 min and reported as mean percent of theoretical concentration (MPT) with associated relative standard deviation (RSD). All experiments were performed in triplicate at room temperature. At t = 0 min, TXA remained stable when mixed with 0.9% NS, 0.1% CHX, 10% BTD, 3% H₂ O₂ , and 1.5% H₂ O₂ (MPT range: 102.0%-105.0%, RSD range: 0.80%-2.92%). Only 0.5% Dakin's led to significant degradation of TXA at t = 0 min (MPT: 14.3%, RSD:1.28%). At t = 120 min, TXA stability persisted for all compounds except Dakin's 0.5% (MPT: 18.4%, RSD: 28.7%). TXA efficacy may be significantly diminished when 0.5% Dakin's is used as an intraoperative irrigation solution. CHX, BTD, and H₂ O₂ do not degrade TXA.

Accuracy Verification of Four-Dimensional CT Analysis of Knee Joint Movements: A Pilot Study Using a Knee Joint Model and Motion-Capture System

Objective This study aimed to use the optical motion-capture method to verify the accuracy of four-dimensional computed tomography (4D-CT) analysis of knee joint movement. Methods One static CT and three 4D-CT examinations of the knee joint model were obtained. The knee joint model was passively moved in the CT gantry during 4D-CT acquisitions. 4D-CT and static CT examinations were matched to perform 3D-3D registration. An optical-motion capture system recorded the position-posture of the knee joint model simultaneously with the 4D-CT acquisitions. Reference axes (X, Y, and Z directions) were defined based on static CT and applied to 4D-CT and the optical-motion capture system. Using the position-posture of the motion capture system as a reference standard, the position-posture measurements using 4D-CT were compared to these values, and the accuracy of the 4D-CT analysis of knee joint movements was quantitatively assessed. Results The position-posture measurements obtained from 4D-CT showed a similar tendency to those obtained from the motion-capture system. In the femorotibial joint, the difference in the spatial orientation between the two measurements was 0.7 mm in the X direction, 0.9 mm in the Y direction, and 2.8 mm in the Z direction. The difference in angle was 1.9° in the varus/valgus direction, 1.1° in the internal/external rotation, and 1.8° in extension/flexion. In the patellofemoral joint, the difference between the two measurements was 0.9 mm in the X direction, 1.3 mm in the Y direction, and 1.2 mm in the Z direction. The difference in angle was 0.9° for varus/valgus, 1.1° for internal/external rotation, and 1.3° for extension/flexion. Conclusions 4D-CT with 3D-3D registration could record the position-posture of knee joint movements with an error of less than 3 mm and less than 2° when compared with the highly accurate optical-motion capture system. Knee joint movement analysis using 4D-CT with 3D-3D registration showed excellent accuracy for in vivo applications.

Optimal surgical treatment for periprosthetic distal femoral fractures after total knee arthroplasty: a Bayesian-based network analysis

BACKGROUND

The surgical methods for periprosthetic distal femoral fractures (PDFFs) after total knee arthroplasty included locking compression plate (LCP), retrograde intramedullary nailing (RIMN), and distal femoral replacement (DFR). However, the optimal treatment remains controversial. We performed a network meta-analysis (NMA) to provide the optimal surgical method for PDFFs.

MATERIALS AND METHODS

Electronic databases, including Embase, Web of Science, Cochrane Library, and PubMed, were searched for studies that compared LCP, RIMN, and DFR for PDFFs. The quality of the included studies was assessed according to the Newcastle-Ottawa scale. Pairwise meta-analysis was performed by Review Manager version 5.4. The NMA was conducted in Aggregate Data Drug Information System software version 1.16.5. We calculated odds ratios (ORs) and 95% confidence intervals (CIs) for postoperative complications and reoperations.

RESULTS

A total of 19 studies and 1198 patients were included, of whom 733 for LCP, 282 for RIMN, and 183 for DFR. Pairwise meta-analysis comparing LCP to RIMN and LCP to DFR showed no significant difference in complications and reoperations except that RIMN had a higher risk of malunion comparing to LCP (OR 3.05; 95% CI 1.46-6.34; P = 0.003). No statistically significant effects were found in the NMA of overall complications, infection, and reoperation. However, results of rank probabilities showed that DFR ranked best in overall complications and reoperation, RIMN ranked best in infection but worst in reoperation, and LCP ranked worst in infection and middle in reoperation.

DISCUSSION

We found similar complication rate and reoperation rate between LCP, RIMN, and DFR. The results of rank probabilities favored DFR, and further studies with high-level evidence are expected to verify the optimal surgical method for PDFFs.

LEVEL OF EVIDENCE

Level II; network meta-analysis.

Periprosthetic distal femur fractures treated by retrograde intramedullary nails with a 10-degree distal bend achieve significantly better post-operative radiographic alignment when compared to conventional retrograde nails

INTRODUCTION

Periprosthetic distal femur fractures (PPDFFs) are a common complication after total knee arthroplasty (TKA). In the setting of well-fixed TKA components, treatment options include retrograde intramedullary nailing (rIMN) or lateral locked plating. Treatment with rIMN has historically been associated with potential for extension deformity when using conventional nails. We hypothesized that the PPDFFs treated with an intramedullary nail with a specifically designed 10-degree distal bend for periprosthetic fractures would result in improved post-operative sagittal alignment compared to conventional intramedullary nails.

MATERIALS AND METHODS

The study was conducted at a level-1 trauma center over a 12-year period (2010 - 2022). Patients over the age of 18 who sustained a PPDFF treated with rIMN were identified. The primary outcomes of the study were post-operative coronal and sagittal alignment determined by reviewing post-operative radiographs.

RESULTS

A total of 50 patients were included. Twenty-three patients were treated with a rIMN with a 10° distal bend. Twenty-seven patients were treated with a rIMN with distal bend of 5° The mean aPDFA for the 10° distal bend group was 81.7° compared to 92.8° in the 5° distal bend group (p<0.001). There were 3/23 (13%) significant sagittal plane deformities the 10° distal bend group compared to 11/27 (41%) in the 5° distal bend group (p = 0.03). There was one patient with a post-operative extension deformity in the 10° distal bend group compared to 11 patients in the 5° distal bend group (p = 0.02).

CONCLUSION

Retrograde intramedullary nailing of PPDFF with a 10° distal bend results in significantly better alignment in the sagittal plane when compared to a conventional 5° nail. The use of a 5° nail resulted in an extension deformity significantly more frequently. We therefore recommend the utilization of a rIMN with a 10° distal bend when treating PPDFFs.

SUMMARY

Periprosthetic distal femur fractures are a common complication following total knee arthroplasty. While several studies report on the use of retrograde intramedullary nails in the treatment of periprosthetic distal femur fractures, there are limited reports of the use of a novel retrograde intramedullary nail with a 10° distal bend in the treatment of these injuries. Herein we present a radiographic study comparing coronal and sagittal postoperative alignment following treatment with retrograde intramedullary nails with a 10° distal bend versus conventional retrograde nails with a 5° distal bend.

Biomechanical analysis of different fixation methods for Rorabeck II supracondylar femoral fractures after total knee arthroplasty

BACKGROUND

Locking plate (LP) and retrograde intramedullary nailing (RIMN) are widely used to fix Rorabeck II supracondylar femoral fractures after total knee arthroplasty (TKA). The biomechanical properties of the implant used for treatment influence its longevity. Therefore, we aimed to evaluate the biomechanical stability of different fixations using finite element analysis.

METHODS

Seven finite element models (FEMs) were established, including LP groups (short LP, long LP, and double LP), RIMN groups (short RIMN and long RIMN), and mixed groups (long LP with short RIMN and long LP with long RIMN). The stress of the implants around the fracture area was calculated to evaluate the biomechanical stability under loads.

RESULTS

Stress was mainly distributed around the fracture area in all models. The stress-shielding phenomenon was most evident in the short LP. The trend in maximum equivalent stress values of implants around the fracture area for the seven internal fixations was: short LP (324.63 MPa) > short RIMN (306.37 MPa) > long LP (275.06 MPa) > long RIMN (262.74 MPa) > double LP (203.19 MPa) > long LP with short RIMN (124.42 MPa) > long LP with long RIMN (112.41 MPa). We found that the double LP can better disperse the stress than a single LP, and a long LP with long RIMN can prevent stress concentration and make the stress distribution more uniform.

CONCLUSION

From the perspective of biomechanics, long LP with long RIMN can stabilize fractures and avoid stress concentration in Rorabeck II supracondylar femoral fractures after TKA.

Comparison of survival rates between total knee arthroplasty after a previous anterior cruciate ligament reconstruction and primary total knee arthroplasty via propensity score matching

INTRODUCTION

Although the survival rate of total knee arthroplasty (TKA) in patients treated with anterior cruciate ligament reconstruction (ACLR) is not as favorable as that in patients treated with primary TKA without ligament reconstruction, the exact survival rates and complications associated with these procedures are still controversial. Therefore, the purpose of the current study was to compare the revision rates of TKA in patients with knee osteoarthritis (OA) with a previous ACLR and those of patients with primary TKA with no history of knee surgery by using propensity score matching analysis.

MATERIALS AND METHODS

A list of patients who underwent TKA from January 1, 2008 to May 31, 2019 was obtained from the Korean National Health Insurance database. Among these, 460 patients underwent TKA in a knee with a previous ACLR and 569,766 patients who underwent primary TKA due to degenerative OA. We performed propensity scoring matching to compare the revision rates including septic revision due to prosthetic joint infection after TKA and perioperative complication rates within 90 days after revision TKA between the two groups.

RESULTS

Matched patients were assigned to one of the two groups (group A: 2,201 patients who underwent TKA due to primary OA, group B: 448 patients who underwent TKA in a knee with a previous ACLR) based on the propensity score. The total number of revisions per 1000 person-years was significantly higher in group B than in group A (10.16 vs 4.66, respectively). Group B showed a higher risk of revision than group A at 10 years post-TKA (hazard ratio: 2.49, 95% confidence interval: 1.30-4.77). However, group B showed a similar risk of septic revision as group A (p = 0.44). Perioperative complications within 90 days after TKA showed no significant differences between the groups.

CONCLUSIONS

Surgeons should be aware of the relatively higher revision rate of TKA in patients who had previously undergone an ACLR compared to that in patients who underwent primary TKA.

Computer-based analysis of different component positions and insert thicknesses on tibio-femoral and patello-femoral joint dynamics after cruciate-retaining total knee replacement

BACKGROUND

Positioning of the implant components and tibial insert thickness constitute critical aspects of total knee replacement (TKR) that influence the postoperative knee joint dynamics. This study aimed to investigate the impact of implant component positioning (anterior-posterior and medio-lateral shift) and varying tibial insert thickness on the tibio-femoral (TF) and patello-femoral (PF) joint kinematics and contact forces after cruciate-retaining (CR)-TKR.

METHOD

A validated musculoskeletal multibody simulation (MMBS) model with a fixed-bearing CR-TKR during a squat motion up to 90° knee flexion was deployed to calculate PF and TF joint dynamics for varied implant component positions and tibial insert thicknesses. Evaluation was performed consecutively by comparing the respective knee joint parameters (e.g. contact force, quadriceps muscle force, joint kinematics) to a reference implant position.

RESULTS

The PF contact forces were mostly affected by the anterior-posterior as well as medio-lateral positioning of the femoral component (by 3 mm anterior up to 31 % and by 6 mm lateral up to 14 %). TF contact forces were considerably altered by tibial insert thickness (24 % in case of + 4 mm increase) and by the anterior-posterior position of the femoral component (by 3 mm posterior up to 16 %). Concerning PF kinematics, a medialised femoral component by 6 mm increased the lateral patellar tilt by more than 5°.

CONCLUSIONS

Our results indicate that regarding PF kinematics and contact forces the positioning of the femoral component was more critical than the tibial component. The positioning of the femoral component in anterior-posterior direction on and PF contact force was evident. Orthopaedic surgeons should strictly monitor the anterior-posterior as well as the medio-lateral position of the femoral component and the insert thickness.

Does Aseptic Revision Risk Differ for Primary Total Knee Arthroplasty Patients Who Have and Do not Have a Prior Primary or Revision Arthroplasty?

BACKGROUND

We sought to evaluate the risk of aseptic revision in total knee arthroplasty (TKA) patients who have and do not have a history of primary or revision arthroplasty of a different major joint.

METHODS

We conducted a matched cohort study using data from Kaiser Permanente's arthroplasty registries. Patients who underwent primary unilateral TKA (index knee) were identified (2009-2018). Two matches based on exposure history were performed: (1) 33,714 TKAs with a history of primary arthroplasty of a different joint (contralateral knee, either hip, and/or either shoulder) were matched to 67,121 TKAs without an arthroplasty history and (2) 597 TKAs with a history of aseptic revision in a different joint were matched to 1,190 TKAs with a history of a prior arthroplasty in a different joint, but without any revision. After the matches were performed, Cox regressions were used to evaluate aseptic revision risk of the index knee using the no history groups as the reference in regression models.

RESULTS

No difference in aseptic revision risk for the index knee was observed when comparing patients who had a prior primary arthroplasty in a different joint to those who did not have an arthroplasty history (hazard ratio = 0.95, 95% CI = 0.86-1.06). Those patients who did not have any prior aseptic revision history in a different joint had higher risk of aseptic revision in the index knee (hazard ratio = 2.06, 95% CI = 1.17-3.63).

CONCLUSION

Patients who had a prior revision history had over a 2-fold higher risk of aseptic revision in the index knee, warranting close surveillance of these patients.

LEVEL OF EVIDENCE

Level III.

The estimated lifetime risk of revision after primary knee arthroplasty is influenced by age, sex, and indication

Aims

The aim of this study was to assess factors associated with the estimated lifetime risk of revision surgery after primary knee arthroplasty (KA).

Methods

All patients from the Scottish Arthroplasty Project dataset undergoing primary KA during the period 1 January 1998 to 31 December 2019 were included. The cumulative incidence function for revision and death was calculated up to 20 years. Adjusted analyses used cause-specific Cox regression modelling to determine the influence of patient factors. The lifetime risk was calculated as a percentage for patients aged between 45 and 99 years using multiple-decrement life table methodology.

Results

The estimated lifetime risk of revision ranged between 32.7% (95% confidence interval (CI) 22.6 to 47.3) for patients aged 45 to 49 years and 0.6% (95% CI 0.1 to 4.5) for patients aged over 90 years. At 20 years, the overall cumulative incidence of revision (6.8% (95% CI 6.6 to 7.0)) was significantly less than that of death (66.3% (95% CI 65.4 to 67.1)). Adjusted analyses demonstrated converse effect of increasing age on risk of revision (hazard ratio (HR) 0.5 (95% CI 0.5 to 0.6)) and death (HR 3.6 (95% CI 3.4 to 3.7)). Male sex was associated with increased risks of revision (HR 1.1 (95% CI 1.1 to 1.2); p < 0.001) and death (HR 1.4 (95% CI 1.3 to 1.4); p < 0.001). Compared to patients undergoing primary KA for osteoarthritis, patients with inflammatory arthropathy had a higher risk of death (HR 1.7 (95% CI 1.7 to 1.8); p < 0.001), but were less likely to be revised (HR 0.9 (95% CI 0.7 to 1.0); p < 0.001). Patients with a greater number of comorbidities (HR 1.4 (95% CI 1.3 to 1.4)) and greater levels of socioeconomic deprivation (HR 1.4 (95% CI 1.4 to 1.5)) were at increased risk of death, but neither increased the risk of revision.

Conclusion

The estimated lifetime risk of revision KA varied depending on patient sex, age, and underlying diagnosis. Patients aged between 45 and 49 years had a one in three risk of undergoing revision surgery within their lifetime, which decreased with age to one in 159 in those aged 90 years or more. Cite this article: Bone Joint J 2022;104-B(12):1313–1322.

Decreased serum superoxide dismutase concentration has a high value for the diagnosis of periprosthetic joint infection-a single-center, retrospective study

PURPOSE

As the most serious complication of total knee arthroplasty (TKA), periprosthetic joint infection (PJI) often leads to disastrous consequences. An accurate preoperative diagnosis plays a significant role in saving prostheses and optimizing treatment outcomes. Through this retrospective case-control study, we aimed to investigate the potential of superoxide dismutase (SOD) as a novel serum biomarker in the diagnosis of PJI.

METHODS

We conducted a retrospective review of all patients who underwent TKA and received adequate follow-ups in our hospital from June 2015 to December 2021. A total of 50 patients were enrolled in the PJI group based on the 2018 International Consensus Meeting (ICM) criteria. Besides that, we enrolled 100 patients who underwent TKA in the same period and had a good postoperative course in the control group. Patient characteristics, comorbidities, laboratory results (serum, synovial, and microbial), and intraoperative findings (purulence and histopathology) were documented and compared by univariate analysis. Receiver operating characteristic (ROC) analysis was used to determine the sensitivity, specificity, and diagnostic performance.

RESULTS

The median serum SOD level in the PJI and control group was 135.95 ± 24.47 U/ml (IQR, 111.85-158.30 U/ml) and 173.83 ± 13.9 U/ml (IQR,162.83-183.5 U/ml) (p < 0.05), respectively. With the calculated cutoff of SOD at 149.5U/L, the area under the ROC curve (AUC), sensitivity, specificity, positive predictive value (PPV), and negative predictive value (NPV), were 0.919, 0.72, 0.97, 0.923, and 0.874, respectively. In subgroup analysis, the specificity of SOD in diagnosing culture-negative PJI remained extremely high (0.98). Combined diagnosis of serum SOD and C-reactive protein (CRP) made AUC increase to 0.972.

CONCLUSION

Serum SOD showed great potential in the diagnosis of PJI.

Radiologists should use the hip-knee-ankle angle rather than the mechanical axis deviation to describe knee alignment

OBJECTIVE

Preoperative and postoperative coronal knee alignment is an important predictor of total knee arthroplasty (TKA) failure. Radiologists often report the mechanical axis deviation (MAD) rather than hip-knee-ankle angle (HKAA) to describe coronal knee alignment. The aim of this study is to evaluate (i) how well the MAD predicts the HKAA; (ii) if patient height and sex affect the performance of the MAD; and (iii) if the MAD could be measured faster than the HKAA.

MATERIALS AND METHODS

Two hundred patients undergoing hip-to-ankle radiographs for TKA planning were retrospectively reviewed. The MAD and HKAA were measured using previously published methods by the Visage picture archiving and communication systems (PACS) tools. Receiver operator characteristic (ROC) curves were used to evaluate the performance of the MAD to predict HKAA by gender and height. The performance of a linear model was used to predict HKAA from MAD in a prospectively collected cohort of 40 patients. Paired t tests were used for the comparison of time measurement in MAD and HKAA in this cohort.

RESULTS

MAD strongly correlated with HKAA (r = 0.99, p < 0.001); however, the performance of MAD differed by height (p = 0.005) and sex (p < 0.001). There was no significant difference in the time taken to measure HKAA versus MAD (p > 0.05).

CONCLUSION

HKAA should be used instead of the MAD because it is more clinically relevant and takes the same amount of time to be measured.

Comparison of Aseptic Partial- and Full-Component Revision Total Knee Arthroplasty

BACKGROUND

Revision total knee arthroplasty (rTKA) can be performed with isolated tibial, isolated femoral, and combined tibial and femoral component exchange for different indications. Replacement of only 1 fixed component in rTKA leads to shorter operative times and decreased complexity. We sought to compare functional outcomes and rates of rerevision in patients undergoing partial and full rTKA.

METHODS

This retrospective study examined all aseptic rTKA patients with a minimum follow-up of 2 years in a single center between September 2011 and December 2019. Patients were divided into two groups: full rTKA (F-rTKA) if both components (femoral and tibial) were revised and partial rTKA (P-rTKA) if only 1 component was revised. A total of 293 patients (P-rTKA = 76, F-rTKA = 217) were included.

RESULTS

P-rTKA patients had significantly shorter surgical time (109 ± 37 Versus. 141 ± 44 minutes, P < .001). At mean follow-up of 4.2 (range 2.2-6.2) years, rerevision rates did not significantly differ between groups (11.8 Versus. 16.1%, P = .358). Improvements in postoperative Visual Analogue Scale (VAS) pain and Knee Injury and Osteoarthritis Scale (KOOS), Joint Replacement scores were similar as well (P = .100 and P = .140, respectively). For patients undergoing rTKA due to aseptic loosening, freedom from rerevision due to aseptic loosening was similar between groups (100 Versus. 97.8%, P = .321). For patients undergoing rTKA due to instability, freedom from rerevision due to instability did not significantly differ as well (100 Versus. 98.1%, P = .683). In the P-rTKA cohort, freedom from all-cause and aseptic revision of preserved components was 96.1% and 98.7% at the 2-year follow-up.

CONCLUSION

Compared to F-rTKA, P-rTKA yielded similar functional outcomes and implant survivorship with shorter surgical time. When indications and component compatibility allow for such a procedure, surgeons can expect good outcomes when performing P-rTKA.

Comparison of locking compression plate and distal femoral replacement for periprosthetic distal femoral fractures: a retrospective study

OBJECTIVE

To compare the clinical outcomes of locking compression plate (LCP) and distal femoral replacement (DFR) for periprosthetic distal femoral fractures (PDFFs) after total knee arthroplasty.

METHODS

This retrospective study identified patients with PDFFs in an institutional database between January 2012 and December 2021. Demographic data and clinical outcomes, including postoperative complications, reoperation, 1-year mortality, Knee Society Scores (KSS) and Knee Society Functional Score (KSFS) were analysed.

RESULTS

In total, 12 patients treated with LCP and six patients treated with DFR were included. There was no significant difference between the LCP and DFR groups in terms of postoperative complications (25.0% versus 33.3%, respectively), reoperation (8.3% versus 0.0%), respectively, 1-year mortality (8.3% versus 16.7%, respectively) or mean ± SD KSS (80.3 ± 8.3 versus 78.0 ± 2.5, respectively). However, the mean ± SD KSFS was significantly better for patients with LCP than for those with DFR (51.8 ± 12.5 versus 37.0 ± 6.7, respectively).

CONCLUSION

DFR provides similar clinical outcomes compared with LCP for PDFFs. Patients with advanced age may benefit from DFR to allow early weight bearing.

Interventions for treating fractures of the distal femur in adults

BACKGROUND

Fractures of the distal femur (the far end of the thigh bone just above the knee) are a considerable cause of morbidity. Various different surgical and non-surgical treatments have been used in the management of these injuries but the best treatment remains unknown.

OBJECTIVES

To evaluate the benefits and harms of interventions for treating fractures of the distal femur in adults.

SEARCH METHODS

We used standard, extensive Cochrane search methods. The latest search date was October 2021.

SELECTION CRITERIA

We included randomised and quasi-randomised controlled trials in adults comparing interventions for treating fractures of the distal femur. Interventions included surgical implants (retrograde intramedullary nail (RIMN), fixed-angle devices, non-locking plate fixation, locking plate, internal fixation, distal femoral replacement, mono-axial plates, poly-axial plates and condylar buttress plates) and non-surgical management.

DATA COLLECTION AND ANALYSIS

We used standard Cochrane methods. Our critical outcomes were validated patient-reported outcome measures (PROMs), direct adverse events, participant-reported quality of life (QoL) and pain scores. Our other important outcomes were adverse events indirectly related to intervention, symptomatic non-union, malunion and resource use. We used GRADE to assess certainty of evidence for each outcome.

MAIN RESULTS

We included 14 studies with 753 participants: 13 studies compared different surgical interventions, and one study compared surgical with non-surgical management. Here, we report the effects for RIMN compared with locking plates. Three studies (221 participants) reported this comparison; it included the largest study population and these are the two most commonly used devices in contemporary orthopaedic trauma practice. Studies used three different tools to assess PROMs. We found very-low certainty evidence for lower Disability Rating Index scores after RIMN at short-term follow-up favouring RIMN (mean difference (MD) -21.90, 95% confidence interval (CI) -38.16 to -5.64; 1 study, 12 participants) and low-certainty evidence of little or no difference at long-term follow-up (standardised mean difference (SMD) -0.22, 95% CI -0.50 to 0.06; 2 studies, 198 participants). Re-expressing the SMD of the long-term follow-up data to Knee Society Score (KSS) used by one study found no clinical benefit of RIMN, based on a minimal clinically important difference of 9 points (MD 2.47, 95% CI -6.18 to 0.74). The effect on QoL was very uncertain at four months (MD 0.01, 95% CI -0.42 to 0.44; 1 study, 14 participants) and one year (MD 0.10, 95% CI -0.01 to 0.21; 1 study, 156 participants); this evidence was very low certainty. For direct adverse events, studies reported reoperation, loss of fixation, superficial and deep infection, haematoma formation and implant loosening. Effects for all events were imprecise with the possibility of benefit or harm for both treatments. We considered reoperation the most clinically relevant. There was very low-certainty evidence of little or no difference in reoperation between the two implants (risk ratio (RR) 1.48, 95% CI 0.55 to 4.00; 1 study, 104 participants). No studies reported pain.  For other important outcomes, we noted that people treated with RIMN may be more likely to have varus/valgus deformity (RR 2.18, 95% CI 1.09 to 4.37; 1 study, 33 participants; low-certainty evidence). However, we found no evidence of any important differences between treatments in terms of bony union, indirect adverse events, or resource use. Other comparisons of surgical interventions included in the review were: RIMN versus single fixed-angle device (3 studies, 175 participants); RIMN versus non-locking plate fixation (1 study, 18 participants); locking plate versus single fixed-angle device (2 studies, 130 participants); internal fixation versus distal femoral replacement (1 study, 23 participants); mono-axial plates versus poly-axial plates (2 studies, 67 participants); mono-axial plate versus condylar buttress plate (1 study, 78 participants). The certainty of the evidence for outcomes in these comparisons was low to very low, and most effect estimates were imprecise.

AUTHORS' CONCLUSIONS

This review highlights the major limitations of the available evidence concerning current treatment interventions for fractures of the distal femur. The currently available evidence is incomplete and insufficient to inform clinical practice. Priority should be given to randomised controlled trials comparing contemporary treatments for people with fractures of the distal femur. At a minimum, these should report validated patient-reported functional and quality-of-life outcomes at one and two years, with an agreed core outcome set. All trials should be reported in full using the CONSORT guidelines.

No Difference in Revision Rate Between Low Viscosity and High Viscosity Cement Used in Primary Total Knee Arthroplasty

BACKGROUND

Loosening remains one of the most common reasons for revision total knee arthroplasty (TKA). Cement viscosity has a potential role in reducing revision rates for loosening. The aim of this study was to assess the outcome for loosening of the 5 most used cemented knee prostheses by constraint type, based on the cement viscosity type used.

METHODS

There were 214,708 TKA procedures performed between 1999 and 2020 for a diagnosis of osteoarthritis using the 5 most commonly used minimally stabilized, posterior stabilized, and medial pivot design cemented tibial components. Only procedures with a cemented tibial component were included. Outcomes for two different cement viscosities, 140,060 high viscosity and 74,648 low viscosity cement, were compared for each fixation type within each of the three stability groups.

RESULTS

There was no difference in a risk of all-cause revision when high viscosity cement was used compared to low viscosity cement for minimally stabilized prostheses (hazards ratio [HR] 1.07 [95% CI 0.99-1.15], P = .09), posterior stabilized prostheses (HR 1.03 [95% CI 0.95-1.11], P = .53), and medial pivot design prostheses (HR 1.06 [95% CI 0.80-1.41], P = .67). No difference was observed between cement viscosity types for any of the prosthesis constraint types when aseptic loosening was assessed.

CONCLUSIONS

We found no difference in the risk of revision for any reason, or for loosening, with cement viscosity for the most commonly used minimally stabilized, posterior stabilized, and medial pivot TKA. The role of cement viscosity in the risk of TKA revision remains unclear and further research is required.

LEVEL OF EVIDENCE

Level III Retrospective comparative study.

Does the use of 3D-printed cones give a chance to postpone the use of megaprostheses in patients with large bone defects in the knee joint?

Revision procedures and the resulting bone loss are a big challenge for orthopedic surgeons. Therefore, we checked what functional outcomes that 3D-printed cone augments can offer to patients with bone defects (Anderson Orthopedic Research Institute [AORI] classification type 2B and 3) in the knee and whether the use of cones can delay the necessity to use a megaprotheses. Data from 64 patients (M = 22; W = 42) who underwent total knee arthroplasty (TKA) revision were included in the analysis. The Knee Society Clinical Rating System (KSS) and the range of motion in the knee joint were used for the functional assessment. The mean follow-up was 28 months (range: 18–44 months). The survival rate for aseptic loosening at follow-up was 100%. Infection occurred in two (3.1%) patients. The mean KSS score increased from 12.75 points preoperatively to 66.56 postoperatively (p < 0.001). The mean range of motion in the knee changed from 61.15° preoperatively to 115.93° postoperatively (p < 0.001). 3D-printed cone augments seem to be a good solution for patients requiring a TKA revision procedure. When used in patients with bone defects classified as 2B and 3 (AORI), they can be a good alternative, delaying the need for megaprotheses.