Above-knee amputation shows higher complication and mortality rates in line with lower functional outcome compared to knee arthrodesis in severe periprosthetic joint infection.

Aims: In cases of severe periprosthetic joint infection (PJI) of the knee, salvage procedures such as knee arthrodesis (KA) or above-knee amputation (AKA) must be considered. As both treatments result in limitations in quality of life (QoL), we aimed to compare outcomes and factors influencing complication rates, mortality, and mobility. Methods: Patients with PJI of the knee and subsequent KA or AKA between June 2011 and May 2021 were included. Demographic data, comorbidities, and patient history were analyzed. Functional outcomes and QoL were prospectively assessed in both groups with additional treatment-specific scores after AKA. Outcomes, complications, and mortality were evaluated. Results: A total of 98 patients were included, 52 treated with arthrodesis and 47 with AKA. The mean number of revision surgeries between primary arthroplasty and arthrodesis or AKA was 7.85 (SD 5.39). Mean follow-up was 77.7 months (SD 30.9), with a minimum follow-up of two years. Complications requiring further revision surgery occurred in 11.5% of patients after arthrodesis and in 37.0% of AKA patients. Positive intraoperative tissue cultures obtained during AKA was significantly associated with the risk of further surgical revision. Two-year mortality rate of arthrodesis was significantly lower compared to AKA (3.8% vs 28.3%), with age as an independent risk factor in the AKA group. Functional outcomes and QoL were better after arthrodesis compared to AKA. Neuropathic pain was reported by 19 patients after AKA, and only 45.7% of patients were fitted or were intended to be fitted with a prosthesis. One-year infection-free survival after arthrodesis was 88.5%, compared to 78.5% after AKA. Conclusion: Above-knee amputation in PJI results in high complication and mortality rates and poorer functional outcome compared to arthrodesis. Mortality rates after AKA depend on patient age and mobility, with most patients not able to be fitted with a prosthesis. Therefore, arthrodesis should be preferred whenever possible if salvage procedures are indicated.

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

¼ The demographic profile of candidates for total knee arthroplasty (TKA) is shifting toward younger and more active individuals.¼ While cemented fixation remains the gold standard in TKA, the interest is growing in exploring cementless fixation as a potentially more durable alternative.¼ Advances in manufacturing technologies are enhancing the prospects for superior long-term biological fixation.¼ Current research indicates that intermediate to long-term outcomes of modern cementless TKA designs are comparable with traditional cemented designs.¼ The selection of appropriate patients is critical to the success of cementless fixation techniques in TKA.¼ There is a need for high-quality research to better understand the potential differences and relative benefits of cemented vs. cementless TKA systems.

Effect of body mass index on 30-day complication rate and implant survival rate after simultaneous bilateral unicompartmental knee arthroplasty: a multicentre retrospective study.

OBJECTIVE: The practice of simultaneous bilateral unicompartmental knee arthroplasty (SBUKA) remains a topic of debate, particularly in patients with obesity. Thus, the purpose of this study was to assess the impact of body mass index (BMI) on the 30-day complication rate and the survival rate of the implant following SBUKA. METHODS: We retrospectively examined the clinical records of 245 patients (490 knees) who underwent SBUKA at the Affiliated Hospital of Qingdao University and the Third Hospital of Hebei Medical University between January 2010 and December 2020. Patients were categorised based on their BMI at the time of surgery into four groups: normal weight (BMI 18.5 to 22.9 kg/m2), overweight (BMI 23.0 to 24.9 kg/m2), obese (BMI 25.0 to 29.9 kg/m2), and severely obese (BMI ≥30 kg/m2). Variables such as length of hospital stay, duration of surgery, and costs of hospitalisation were compared across all groups. Additionally, we recorded the 30-day postoperative complication rate and the time from surgery to any required revision. The Kaplan-Meier survival analysis was employed to evaluate and compare the implant survival rates. RESULTS: The follow-up period for the 245 patients ranged from 39 to 114 months, with an average of 77.05±18.71 months. The incidence of complications within 30 days post-surgery did not significantly differ across the groups (χ2 = 1.102, p = 0.777). The implant survival rates from the lowest to the highest BMI groups were 97.14%, 93.9%, 94.44%, and 96.43%, respectively. Both the rate of implant revision (χ2 =1.612, p = 0.657) and the survival curves of the implants (p = 0.639) showed no statistically significant differences among the groups. CONCLUSIONS: BMI did not influence the 30-day complication rate nor the survival rate of implants following SBUKA, suggesting that SBUKA should not be contraindicated based on BMI alone.

Robotic arm-assisted conversion of unicompartmental knee arthroplasty to total knee arthroplasty.

Aims: Robotic arm-assisted surgery offers accurate and reproducible guidance in component positioning and assessment of soft-tissue tensioning during knee arthroplasty, but the feasibility and early outcomes when using this technology for revision surgery remain unknown. The objective of this study was to compare the outcomes of robotic arm-assisted revision of unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) versus primary robotic arm-assisted TKA at short-term follow-up. Methods: This prospective study included 16 patients undergoing robotic arm-assisted revision of UKA to TKA versus 35 matched patients receiving robotic arm-assisted primary TKA. In all study patients, the following data were recorded: operating time, polyethylene liner size, change in haemoglobin concentration (g/dl), length of inpatient stay, postoperative complications, and hip-knee-ankle (HKA) alignment. All procedures were performed using the principles of functional alignment. At most recent follow-up, range of motion (ROM), Forgotten Joint Score (FJS), and Oxford Knee Score (OKS) were collected. Mean follow-up time was 21 months (6 to 36). Results: There were no differences between the two treatment groups with regard to mean change in haemoglobin concentration (p = 0.477), length of stay (LOS, p = 0.172), mean polyethylene thickness (p = 0.065), or postoperative complication rates (p = 0.295). At the most recent follow-up, the primary robotic arm-assisted TKA group had a statistically significantly improved OKS compared with the revision UKA to TKA group (44.6 (SD 2.7) vs 42.3 (SD 2.5); p = 0.004) but there was no difference in the overall ROM (p = 0.056) or FJS between the two treatment groups (86.1 (SD 9.6) vs 84.1 (4.9); p = 0.439). Conclusion: Robotic arm-assisted revision of UKA to TKA was associated with comparable intraoperative blood loss, early postoperative rehabilitation, functional outcomes, and complications to primary robotic TKA at short-term follow-up. Robotic arm-assisted surgery offers a safe and reproducible technique for revising failed UKA to TKA.

Utility of Debridement, Antibiotics, and Implant Retention for Acute Periprosthetic Joint Infection in Revision Total Knee Arthroplasty.

Background: Periprosthetic joint infection (PJI) in revision arthroplasty presents as a challenging complication that is difficult to manage. Debridement, antibiotics, and implant retention (DAIR) is a recognized treatment option, although few studies have investigated success rates in addition to eventual amputation rates for failed cases. Methods: A retrospective review of 365 DAIR cases was performed at a single institution from 2008-2020. Patient records were thoroughly reviewed for inclusion and exclusion criteria by multiple members of the research team, discovering 45 cases met criteria for the study cohort. Demographic information, medical history, culture data, and surgical history, were recorded. DAIR's overall survivorship was evaluated with a Kaplan-Meier (KM) survival curve. Additional KM curves were constructed to compare acute postoperative versus acute hematogenous infections as well as DAIR survivorship relative to infecting organism. Results: DAIR's success rate in revision TKA was 77% at 0.5 years, 56% at 2 years and 46% at 5 years. No significant difference was noted in survivorship when comparing acute postoperative and acute hematogenous cases at 5 years (29 vs 51%, P=0.64). No significance differences in survivorship were noted according to infecting organism (P =0.30). Median follow up duration was significantly lower in the failed DAIR cohort with a median time of 0.5 years in comparison to 1.7 years for the successful DAIR group (P =0.012). There were 20 DAIR cases that failed, 10 of which resulted in eventual amputation. Conclusion: DAIR's success rate for managing acute PJI in revision arthroplasty cases was 46% at 5 years. Of the 20 failed DAIR cases, 10 resulted in eventual amputation. DAIRs utility in managing these complicated PJI cases in the setting of revision arthroplasty is concerning with low success rates and high rates of amputation in failed cases. Level of Evidence: III.

Limited Revision with a Newly Designed Hinge Device for the Treatment of Mega-Prosthesis Hinge Failure: Two Case Reports.

BACKGROUND: Surgical treatment for hinge failure in mega-prosthesis continues to be a challenge. This study introduces a new method for treating hinge failure by using a unilateral prosthesis and hinge revision. CASE PRESENTATION: We here present two patients who underwent mega-prosthesis reconstruction after resection of osteosarcoma in the distal femur. To address the issue of knee hyperextension after mega-prosthesis reconstruction, one patient underwent three revision surgeries, two surgeries were performed using the original hinge, and one surgery involved a newly designed hinge. To resolve the problem of dislocation, one patient underwent three revisions, with the first two revisions not involving hinge replacement and the third revision involving a newly designed hinge. Two replacements of unilateral prosthesis and hinge renovations were successful. CONCLUSIONS: Unilateral prosthesis and newly designed hinge device revision are effective in treating the failure of old-fashioned mega-prosthesis hinges.

Comparing the lower limb joint biomechanics of the Power Knee, C-Leg and Rheo Knee during ramp and stair ambulation.

One of the most significant developments in prosthetic knee technology has been the introduction of the Microprocessor-Controlled Prosthetic Knee (MPK). However, there is a lack of consensus over how different types of MPKs affect performance in different ambulation modes. In this study, we investigated the biomechanical differences in ramp and stair maneuvers when an individual with transfemoral amputation wears three commercial MPKs: the Össur Power Knee, the Össur Rheo Knee and the Ottobock C-Leg 4. The primary outcome variable for this study was the lower limb biological joint work, inclusive of the intact leg and prosthetic side hip. We hypothesized that (1) the Power Knee would result in lower biological work during ascent activities than the C-Leg and Rheo, both passive MPKs, and (2) the C-Leg and Rheo would result in lower biological work during descent activities than the Power Knee. During ramp ascent, the C-Leg was associated with lower biological joint work (p < 0.05) than the Power Knee. However, this relationship did not hold during stair ascent, where the Power Knee showed advantages for stair ascent with net reductions in biological joint work of 14.1% and 23.3% compared to the Rheo and C-leg, respectively. There were no significant differences in biological joint work between the knees during ramp and stair descent, indicating that choice of MPK may not be as important for descent activities. Our results demonstrate that differences are present between different types of MPKs during ascent activities which could prove useful in the prescription of these devices.

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.

[GMK rotating hinge prosthesis. A valid option for complex revision knee prosthetic surgery]. / Prótesis bisagra rotatoria GMK. Una opción válida para la cirugía de revisión protésica compleja de rodilla.

INTRODUCTION: revision joint replacement surgery presents a surgical challenge. The use of rotating hinge prostheses is an option in patients with femorotibial bone defects, ligament insufficiency, or significant deformities. The aim of this study was to evaluate the clinical, functional, and radiological outcomes of a series of patients who underwent surgery using the GMK Hinge (Medacta®) rotational hinge model. MATERIAL AND METHODS: a descriptive, retrospective, and analytical study was conducted on a series of 36 patients, with a mean age of 72.5 years (47-85), operated on by the same surgical team between January 2015 and January 2022. The etiology of revision was chronic infection in 38.9% of cases, instability in 33.3%, aseptic loosening in 19.4%, and stiffness in 8.4%. The Knee Society Score (KSS) and the Forgotten Joint Score (FJS) were used to assess functional outcomes. The degree of femorotibial bone defect was evaluated using the Anderson Orthopaedic Research Institute (AORI) classification. Postoperative complications are also recorded. RESULTS: a total of 36 patients, 17 males and 19 females, were included, with a mean follow-up of 30 months (12-66). Twelve patients had type 1 defects, ten had 2A defects, ten had 2B defects, and two had type 3 defects on the femoral side, with the use of wedges required for asymmetrical defects (21 patients). The predominant tibial defect was type 1 without the need for wedges. The majority achieved a satisfactory outcome on the KSS scale (72.2 ± 9.4), with significant differences compared to the previous KSS (54.3 ± 8.9). A score of 31 (12-67) was also obtained on the FJS scale. Postoperative complications were present in 16.7% of patients. CONCLUSIONS: complex prosthetic revision surgery using a rotating hinge prosthesis represents a suitable therapeutic option, yielding appropriate clinical and functional outcomes, albeit not without complications.

INTRODUCCIÓN: la cirugía de revisión protésica constituye un reto quirúrgico. La utilización de prótesis tipo bisagra rotatoria es una opción en pacientes con defectos óseos femorotibiales, insuficiencia ligamentosa o importantes deformidades. El objetivo del presente estudio es evaluar los resultados clínicos, funcionales y radiológicos de una serie de pacientes intervenidos mediante un modelo de bisagra rotacional GMK Hinge (Medacta®). MATERIAL Y MÉTODOS: estudio descriptivo retrospectivo y analítico que incluyó una serie de 36 pacientes, con edad media de 72.5 años (47-85) intervenidos entre Enero de 2015 y Enero de 2022 por el mismo equipo quirúrgico. La etiología de revisión fue infección crónica en 38.9%, inestabilidad en 33.3%, aflojamiento aséptico en 19.4% y rigidez en 8.4%. Para la evaluación de resultados funcionales se utiliza la escala Knee Society Score (KSS), así como la escala Forgotten Joint Score (FJS). El grado de defecto óseo femorotibial se evaluó mediante la clasificación de Anderson Orthopaedic Research Institute (AORI). También se registraron las complicaciones postquirúrgicas. RESULTADOS: se analizó un total de 36 pacientes, 17 varones y 19 mujeres, con seguimiento medio de 30 meses (12-66). Se encontraron doce pacientes con defectos tipo 1, diez con defectos 2A, diez con defectos 2B y dos con defecto tipo 3 en la vertiente femoral, siendo necesario la utilización de cuñas en defectos asimétricos (21 pacientes). El defecto tibial mayoritario fue el tipo 1 sin necesidad de cuñas. La mayoría obtuvo un resultado satisfactorio en la escala KSS (72.2 ± 9.4), con diferencias significativas respecto al KSS previo (54.3 ± 8.9). Se obtuvo también una puntuación de 31 (12-67) en la escala FJS. Presentaron complicaciones postoperatorias 16.7% de los pacientes. CONCLUSIONES: la cirugía de revisión protésica compleja mediante prótesis tipo bisagra rotacional constituye una correcta opción terapéutica, presentando resultados clínicos y funcionales adecuados, no exentos de complicaciones.

Strains on the human femur after revision total knee arthroplasty: An in vitro study using digital image correlation.

Pain at the tip of the stem of a knee prosthesis (End-of-Stem Pain) is a common problem in revision total knee arthroplasty (TKA). It may be caused by a problematic interaction between stem and bone, but the exact biomechanical correlate is still unknown. On top of this, there is no biomechanical study investigating End-of-Stem Pain at the distal femur using human specimens. Aim of this study was to find out whether the implantation of a revision total knee implant leads to high femoral surface strains at the tip of the stem, which the authors expect to be the biomechanical correlate of End-of-Stem Pain. We implanted 16 rotating hinge knee implants into 16 fresh-frozen human femora using the hybrid fixation technique and comparing two reaming protocols. Afterwards, surface strains on these femora were measured under dynamic load in two different load scenarios (climbing stairs and chair rising) using digital image correlation (DIC) and fracture patterns after overcritical load were analysed. Peak surface strains were found at the tip of the stem in several measurements in both load scenarios. There were no significant differences between the two compared groups (different trial sizes) regarding surface strains and fracture patterns. We conclude that implantation of a long intramedullary stem in revision TKA can lead to high surface strains at the tip of the stem that may be the correlate of femoral End-of-Stem Pain. This finding might allow for a targeted development of future stem designs that can lead to lower surface strains and therefore might reduce End-of-Stem Pain. Digital Image Correlation proved valid for the measurement of surface strains and can be used in the future to test new stem designs in vitro.

Clinical Relevance of Posterior Osteophyte Formation in Ultra-congruent Total Knee Arthroplasty: Midterm Radiographic Rollback and Impingement Analysis.

Background: Posterior femoral condylar osteophytes were frequently observed in patients with the ultra-congruent (UC) deep-dish design prosthesis. Therefore, the purpose of the present study was to verify the clinical relevance of osteophyte formation in the UC design. Methods: From March 2014 to February 2018, a comparative study was conducted on 96 knees using the UC design. They were divided into 2 groups (group 1: osteophyte +, group 2: osteophyte -). Intraoperative findings, indirect femoral rollback assessment using 30° flexion and active full flexion lateral radiographs, serial change of the osteophyte, and outcomes were compared. Results: The mean follow-up period was 49.35 ± 3.47 months in group 1 and 47.52 ± 3.37 months in group 2. Posterior component coverage was significantly different between the groups: group 1 exhibited more underhang and group 2 exhibited more overhang (p = 0.022). On the indirect assessment of the femoral rollback, there was a statistically significant difference in deep flexion and change in distance (p < 0.001 and p < 0.001, respectively). There was no statistical difference between the 2 groups in the American Knee Society knee and function score, and group 2 showed significant improvement in pain compared to group 1 in Western Ontario and McMaster University Arthritis Index pain score (p = 0.029). Conclusions: Posterior condylar osteophyte formation was related to posterior impingement. It was more frequently observed in the underhang of the femoral component and insufficient femoral rollback. In addition, it changed with time and caused negative effects, including a gradual decrease in flexion and more pain.

Periprosthetic giant cell tumour of the tibia: en bloc resection and megaprosthesis revision.

We present a case detailing the diagnosis and management of a periprosthetic giant cell tumour in a female patient in her 70s, who had undergone total knee arthroplasty (TKA) for primary osteoarthritis in her right knee 7 years prior. The patient reported 4 months of painful weight-bearing. Various imaging modalities, including plain radiographs, CT scans and MRI, revealed a sizeable lytic lesion beneath the TKA prosthesis, along with loosening of the tibial component.Blood tests and analyses of synovial fluid ruled out periprosthetic joint infection, and a biopsy confirmed the diagnosis of a giant cell tumour of the bone. Treatment entailed en bloc resection of the tumour and revision of the TKA using a hinged, oncological-type megaprosthesis. Surgical procedures involved careful resection of the proximal tibia, preservation of vasculature and the creation of a medial gastrocnemius muscle flap. Following surgery, the patient underwent supervised rehabilitation with a functional brace.

C-Reactive Protein and Erythrocyte Sedimentation Rates after Total and Unicompartmental Knee Arthroplasty-Less Implant Equals Quicker Normalization.

Postoperative follow up after total or unicondylar knee arthroplasty (UKA) includes C-reactive protein (CRP) and erythrocyte sedimentation rate (ESR) to scan for and possibly diagnose a periprosthetic joint infection (PJI). The aim of this study was to describe the postoperative changes in CRP and ESR values after UKA and compare them with values obtained after TKA. Patients operated on between 2020 and 2022 were eligible for this retrospective study. Inclusion criteria were patients with at least 4 postoperative visits associated with blood test screening for PJI, aged > 45, with uneventful follow-up for the first 90 days. Exclusion criteria were a history of chronic inflammatory disease, revision for any reason, and readmission for any reason. Blood samples were collected on the 3rd, 15th, and 30th postoperative days and once between the 45th and the 90th day. The mean and peak values were compared between the two groups. The study included 277 patients (243 TKAs and 34 UKAs). Mean age was significantly lower in the UKA group (67.2 ± 7.5 vs. 60.0 ± 5.9). On the 3rd and the 15th postoperative day, the UKA patients had significantly lower ESR and CRP levels. The levels normalized after the first month. While the TKA patients showed higher values, the trend normalized after the 30th day. CRP and ESR values rose significantly after TKA and persisted up to the 15th day postoperatively. CRP and ESR values normalized faster in patients undergoing UKA. Patients > 65 had higher CRP and ESR values during their routine follow-ups.

Biomechanical improvements in gait following medial pivot knee implant surgery.

BACKGROUND: Total knee replacements are used to improve function and reduce pain in patients with advanced osteoarthritis. The medially stabilising implant is designed to mimic a healthy knee. This study aims to provide a comprehensive analysis of the kinematics and kinetics of a medially stabilising knee implant, comparing it to a healthy control group, as well as to its pre-operative state and the contralateral limb. METHODS: Sixteen total knee replacement patients and ten healthy participants were recruited. Patients underwent testing 4-6 weeks before surgery and repeated the same tests 12 months after surgery. Healthy participants completed the same tests at a single time point. All participants completed three walking trials: kinematics was captured with eight cameras; kinetics with in-ground force plates. Subject-specific musculoskeletal models were developed in OpenSim. Inverse kinematics and inverse dynamics were used to determine gait parameters. Joint angles and joint moments were evaluated using Statistical Parametric Mapping. Patient-reported outcome measures were also collected at both time points. FINDINGS: Spatiotemporal results indicate significant differences in velocity and step length between pre-operative patients and control participants. Differences are observed in the adduction angles between the contralateral and ipsilateral limbs pre-operatively. Postoperatively, there was an increase in the 1st peak flexion moment, reduced adduction moment and reduced internal rotation moment. In PROMs, patients all report improvements in pain levels and high satisfaction levels following surgery. INTERPRETATIONS: Following medial stabilising total knee arthroplasty, patients displayed improved clinical parameters and joint moments reflecting a shift towards more normal, healthy gait.

A novel post-processing technique for correcting symmetric implant ambiguity in measuring total knee arthroplasty kinematics from single-plane fluoroscopy.

Recent advancements in computer vision and machine learning enable autonomous measurement of total knee arthroplasty kinematics through single-plane fluoroscopy. However, symmetric components present challenges in optimization routines, causing "symmetry traps" and ambiguous poses. Achieving clinically robust kinematics measurement requires addressing this issue. We devised an algorithm that converts a "true" pose to its corresponding "symmetry trap" orientation. From a dataset of nearly 13,000 human supervised kinematics, this algorithm constructs an augmented dataset of "true" and "symmetry trap" kinematics, used to train eight classification machine learning algorithms. The outputs from the highest-performing algorithm classify kinematics sequences as 'obviously true' or 'potentially ambiguous.' We construct a spline through 'obviously true' poses, and 'ambiguous' poses are compared to the spline to determine correct orientation. The machine learning algorithms achieved 88-94% accuracy on our internal test set and 91-93% on our external test set. Applying our spline algorithm to kinematics sequences yielded 91.1% accuracy, 94% specificity, but 67% sensitivity. The accuracy of standard ML algorithms for implants within 5 degrees of a pure-lateral view was 71%, rising to 88% beyond 5 degrees. This pioneering study systematizes addressing model-image registration issues with symmetric tibial implants. High accuracy suggests potential use of ML algorithms to mitigate shape-ambiguity errors in pose measurements from single-plane fluoroscopy. Our results also suggest an imaging protocol for measuring kinematics that favors more oblique viewing angles, which could further disambiguate "true" and "symmetry trap" poses.

Comparison of the in vivo kinematics between robotic-assisted Bi-cruciate retaining and Bi-cruciate stabilised total knee arthroplasty.

BACKGROUND: Up to 20% of patients remain unsatisfied after total knee arthroplasty (TKA), prompting the development of new implants. Bi-Cruciate Retaining (BCR) TKA preserves both the anterior cruciate ligament (ACL) and posterior cruciate ligament (PCL), with the ACL beneficial for its proprioceptive qualities. The Bi-Cruciate Stabilised (BCS) TKA substitutes the ACL and PCL with a unique dual cam-post mechanism. Robotics improve accuracy and facilitate technically demanding TKA. METHODS: This was a retrospective case-control study recruited from two centres. Measured outcomes included kinematic analysis, proprioception, and functional outcomes. RESULTS: There was a significantly larger maximum flexion angle and range of flexion to extension in sit-to-stand and stairs in BCR when compared to BCS. Further analysis revealed more similarities between BCR and normal native knees. Proprioception and functional scores did not have any statistical difference. CONCLUSION: BCR TKA demonstrated better knee flexion in weight-bearing active range of motion and showed similarities with normal knee kinematics.

Epidemiology and Risk Factors for Revision Total Knee Arthroplasty in Chinese Patients: A Retrospective Study in Changchun, Jilin Province, China.

BACKGROUND Over the past decades, total knee arthroplasty (TKA) in China has increased substantially. Owing to a lack of a joint registry, there is restricted information concerning the epidemiology of TKA failures in China. We aimed to (1) investigate the etiology of TKA failures in a cohort of Chinese patients and (2) determine the related demographic and anthropometric risk factors in Jilin, China, to have a look at the actual situation. MATERIAL AND METHODS A total of 1927 primary and 109 revision TKAs performed between April 2014 and May 2022 were analyzed in this retrospective study. Patient demographics and anthropometric measures, the interval from primary TKA to revision procedures, and the mechanisms for primary TKA failure were evaluated. A chi-square test, unpaired t test, and multivariate logistic regression were used to investigate the relationships between different factors and TKA failures. RESULTS The leading failure mechanism was infection (53.3%), followed by aseptic loosening (21.5%), stiffness (15.0%), instability (3.7%), malposition (2.8%), periprosthetic fractures (2.8%), and extensor mechanism disruption (0.9%). Infection (59.7%) was the main reason for early revision. Aseptic loosening (43.3%) was the leading cause of late revision. The male ratio in infection patients was higher (35.1% vs 20.6%). The smoking rate in patients with revision and infection was higher (18.9%, 23.9% vs 7%) than in primary patients. There was no difference in BMI between groups. CONCLUSIONS The leading cause of revision TKA in Jilin, China, was infection, followed by aseptic loosening and stiffness. Sex and smoking history were associated with TKA failures in this region.

Establishing femoral component rotation using a dynamic tensioner does not improve patellar position after total knee replacement with use of anatomic implants: A case-control study.

BACKGROUND: Anterior knee pain (AKP) is one of the reasons for dissatisfaction after total knee replacement (TKR). It may result from patellofemoral joint dysfunction, caused by improper rotation of implant components. The aim of this study was to analyze patella positioning in patients after standard measured resection TKR and TKR with a use of a dynamic tensioner, and to assess the frequency of AKP, range of motion (ROM), and patient-reported outcome measures 6 weeks and 3 months postoperatively. METHODS: The study consisted of 127 patients who underwent TKR. Eighty-nine of them treated with use of the dynamic tensioner FUZION formed the study group; the remainder formed the control group. All participants received cemented PERSONA MC without patella resurfacing. All patients had a standard anteroposterior, lateral weight-bearing, long-leg view X-ray and computed tomography examination in 30° of knee flexion following the procedure. RESULTS: There were no significant differences between the study and the control groups regarding: posterior condylar axis (PCA)-patella angle, surgical transepicondylar axis (sTEA)-patella angle, PCA-sTEA angle, deviation from 90° in PCA-patella, sTEA-patella and PCA-sTEA angles. No significant difference was found in a ratio of obtaining PCA-patella angle deviation of more than 3°. Regarding clinical parameters, statistically and questionablly clinically significant difference in favor of the Study Group was found in Forgotten Joint Score 6 weeks and 3 months post-operativley and ROM 6 weeks post-operatively. However, such difference was not found by analyzing ROM 3 months post-operatively, AKP and Western Ontario and McMaster Universities Osteoarthritis Index (WOMAC) scores. CONCLUSION: Compared with the standard 3° of femoral component external rotation, use of a dynamic tensioner does not allow for more accurate restoration of the patellar facet position with reference to the PCA.

Pre-milling technique improves the accuracy of posterior femoral condyle cut and reduces the tibial recut in Oxford unicompartmental knee arthroplasty.

BACKGROUND: Recuts are sometimes needed in UKA because of inadequate posterior tibial cut thickness. We investigated the efficacy of a pre-milling technique (the first milling is done prior to the posterior condylar cut) in Oxford unicompartmental knee arthroplasty to enhance bone cut thickness and to minimize tibial recuts. PATIENTS AND METHODS: Between January 2021 and January 2023, a posterior condyle cut was made before milling in 213 knees in 152 patients (conventional group), while the pre-milling technique was used in 198 knees in 140 patients (pre-milling group). The thickness of the posterior condyle and the rate of tibial recuts were compared between the groups. RESULTS: The bone cut thickness was thinner in the conventional group than in the pre-milling group in small-size (4.7 mm ± 0.6 mm and 5.0 mm ± 0.6 mm, P = 0.0001) and in medium-size (5.1 mm ± 0.5 mm and 5.4 mm ± 0.5 mm, 0.0001) femoral components, whereas there was no difference in large-size femoral components. However, the thickness was still less than the component thickness (5.17 mm for small, 5.57 mm for medium and 6.17 mm for large) in both groups. Tibial recuts were more prevalent in the conventional group than in the pre-milling group (14 knees, 7%, 3 knees 2%, P = 0.002). CONCLUSIONS: The pre-milling technique was found to increase the bone cut thickness in small and medium femoral components, reducing the need for tibial recuts. Further research is warranted to optimize the pre-milling technique and to investigate its long-term impact on patient outcomes.

The peak force to push a trial tibial insert into position cannot be used to select the correct thickness in total knee arthroplasty.

An objective of a total knee arthroplasty (TKA) is to restore native (i.e. healthy) function, and a crucial step is determining the correct insert thickness for each patient. If the insert is too thick, then stiffness results, and if too thin, then instability results. Two methods to determine the insert thickness are by manually assessing the joint laxity and by using a trial insert with goniometric markings that measures the internal-external rotation of the trial with respect to a mark on the femoral component. The former is qualitative and depends on the surgeon's experience and 'feel' and while the latter is quantitative, it can be used only with an insert with medial ball-in-socket conformity. An unexplored method is to measure the force required to push a trial insert into position. To determine whether this method has merit, the push force was measured in 30 patients undergoing unrestricted kinematically aligned TKA using an insert with ball-in-socket medial conformity, a flat lateral surface, and retention of the posterior cruciate ligament. During surgery, the surgeon determined three appropriate thicknesses to test from a selection ranging from 10 mm to 14 mm in 1 mm increments. The peak push forces going from an insert 1 mm thinner than the correct thickness as determined by an insert goniometer and from the correct thickness to 1 mm thicker were measured. Mean peak forces for the different insert thicknesses were 127 ± 104 N, 127 ± 95 N, and 144 ± 96 N for 1 mm thinner, correct, and 1 mm thicker, respectively, and did not differ (p = 0.3210). As a result, measurement of peak force during trial positioning of a tibial insert cannot be used to identify the correct thickness for all insert designs.