Similar kinematic patterns in posterior-stabilized and condylar constrained knee prostheses in revision knee arthroplasty: a prospective cohort study.

Surgeons want to achieve native kinematics in primary total knee arthroplasty (TKA). Cruciate-substituting (CS) implants could restore the knee kinematics more efficiently than posterior-stabilised (PS) TKA. This study aimed to compare gait patterns in patients with CS or PS TKA at 6months. The hypothesis was that CS implants would demonstrate comparable gait parameters to PS implants at 6months. In this prospective case-control study, 38 primary TKA without coronal laxity were divided into 2 groups: 19 cruciate-substituting (CS) and 19 posterior-stabilised (PS) implants. The type of prosthesis was determined according to the surgical period. Exclusion criteria were TKA revision, associated procedures and inability to walk on a treadmill. Gait analysis was conducted on a treadmill 6months postoperatively for each patient with a knee assessment device (KneeKG®). Gait characteristics included analysis in three spatial dimensions (flexion-extension, abduction-adduction, internal-external rotation, anterior-posterior translation). Clinical outcomes (Knee Society Score and Forgotten Joint Score) were compared between both groups at 6months postoperatively. At 6months, the gait analysis did not demonstrate any significant difference between CS and PS implants. The range and the maximum anteroposterior translation were similar in both groups (9.2 ± 6.5mm in CS group vs. 8.1 ± 3mm in PS group (n.s.); and - 5.2 ± 5mm in CS group vs. - 6.3 ± 5.9mm in PS group (n.s.), respectively). The internal/external rotation, the flexion, and the varus angle were similar between CS and PS implants. The KSS Knee score was higher at 6months in the CS group than in the PS group (92.1 ± 5.6 vs. 84.8 ± 8.9 (p < 0.01)). Cruciate-substituting and posterior-stabilised TKA had similar gait patterns at 6months postoperatively, despite a non-equivalent posterior stabilisation system. CS prostheses were an interesting option for primary TKA for knee kinematics restoration without requiring a femoral box. Prospective, case-control study; Level II.

Posterior cruciate ligament (PCL) retention may impact a patient's awareness of their artificial joint following primary total knee arthroplasty (pTKA) due to increased proprioception and more native knee kinematics. Therefore, the purpose of this study was to investigate whether cruciate-retaining (CR) or posterior-stabilized (PS) implants influence the Forgotten Joint Score (FJS-12) following pTKA. We retrospectively reviewed all patients who underwent pTKA with a CR or PS implant at our institute between October 2017 and March 2021. Of the 6,258 patients identified, 5,587 did not have recorded FJS-12 scores at either three months, one year, or two years postoperatively nor a Knee Injury and Osteoarthritis Outcome Score for Joint Replacement (KOOS, JR) preoperatively, three months, or one year postoperatively, and these were considered lost to follow up. Thus, a total of 671 cases were identified and subsequently stratified into two cohorts based on whether they received a CR (n=236, 35%) or PS (n=435, 65%) implant. Patients who received PS implants were further divided into constrained (CoN) and non-constrained (NCoN) liner cohorts. Multivariable linear regression analysis was used to compare patient-reported outcome (PRO) scores. There were no significant differences in PRO scores between CR and PS implants at any time point. Patients in the CoN (n=74) cohort had significantly higher FJS-12 scores at one year (CoN: 56.31 + 25.34 vs NCoN: 42.24 + 27.00, p=0.001) and two years (CoN: 58.52 + 33.71 vs NCoN: 46.97 + 27.44, p=0.013) postoperatively compared to patients in the NCoN (n=361) cohort. Although our analysis demonstrated significant differences in FJS-12 scores at one and two years postoperatively depending upon the liner constraint, there were no significant differences in FJS-12 scores between CR and PS implants. Therefore, while retention of the PCL does not impact patient awareness of their artificial joint, the level of liner constraint may influence outcomes if the PCL is sacrificed.

Golf is a popular sport among patients undergoing total knee arthroplasty (TKA). The golf swing requires significant knee rotation, which may lead to changes in golfing ability postoperatively. The type of implant used may alter the swing mechanics or place different stresses on the knee. The purpose of this study was to evaluate golf performance and subjective stability after TKA and compare outcomes between cruciate-retaining (CR) and posterior-stabilized (PS) implants. Patients with CR implants will experience better stability during the golf swing compared to patients with PS implants. Retrospective cohort study. Level 3. Patients who underwent primary TKA were identified from the medical record and sent an electronic questionnaire focusing on return to play (RTP), performance, pain, and stability during the golf swing. Knee injury and Osteoarthritis Outcome Scores (KOOS) were collected before and at multiple time points after surgery. Patients were surveyed postoperatively and asked to evaluate overall performance, pain, and stability before and after surgery. Outcomes were compared based on implant type. Most patients (81.5%) were able to return to golf at an average of 5.3 ± 3.1 months from surgery. The average postoperative KOOS was 74.6 ± 12.5 in patients able to RTP compared with 64.4 ± 9.5 in those who were not (P < 0.05). Knee pain during golf significantly improved from 6.4 ± 2.1 to 1.8 ± 2.2 (P < 0.01). There were no significant differences in pain, performance, or stability between the CR and PS patients. Most patients can successfully return to golfing after TKA. Knee replacement offers patients reliable pain relief during the golf swing and fewer physical limitations during golf, with no detriment to performance. There is no difference in performance or subjective knee stability based on component type. Understanding associated outcomes of different TKA knee systems allows for unbiased and confident recommendations of either component to golfers receiving total knee replacement.

Measuring patellar height using the lateral active flexion radiograph: Effect of total knee implant design

Prior Patellectomy: A Systematic Review and Meta-Analysis Comparing Cruciate-Retaining and Posterior-Stabilized Total Knee Arthroplasty Survivorship and Reported Outcomes

Functional alignment (FA) has emerged as a personalized strategy in total knee arthroplasty (TKA) to optimize outcomes by accounting for patient-specific anatomical and soft tissue characteristics. Limited evidence exists on how polyethylene insert type, specifically cruciate-substituting (CS) versus posterior-stabilized (PS), impacts clinical outcomes and complications in this context. This retrospective comparative study included 329 patients who underwent robotic-assisted TKA with FA principles with a minimum 2-year follow-up. Patients were divided into two groups: CS or PS implants. CS inserts were selected for patients with an intact posterior cruciate ligament (PCL), while PS inserts were used in cases of PCL insufficiency or significant flexion contractures. Preoperative and post-operative outcomes, including Knee Society Scores (KSS), Forgotten Joint Scores (FJS), range of motion (ROM) and complications, were assessed. Implant survivorship was analyzed using the Kaplan-Meier method. At a median follow-up of 36 months, no significant differences were observed between CS and PS groups in KSS (knee: p = 0.45; function: p = 0.4), FJS (p = 0.7) or ROM (median flexion: 130° in both groups, p = 0.52). Specific complications included intraoperative lateral condyle fractures in the PS group and femoral component revisions due to instability in the CS group. The overall complication rates and implant survivorship were comparable (p = 0.55 and p = 0.85, respectively). This study is the first to evaluate polyethylene insert type in FA and demonstrates that both CS and PS inserts provide comparable outcomes and safety profiles in robotic-assisted TKA. These findings underscore the importance of patient-specific implant selection, with further research needed to assess long-term results. Level III.

This systematic review and meta-analysis aimed to compare the influence of patellar resurfacing following cruciate-retaining (CR) and posterior-stabilized (PS) total knee arthroplasty (TKA) on the incidence of anterior knee pain, knee-specific patient-reported outcome measures, complication rates, and reoperation rates. A systematic review of MEDLINE, PubMed, and Google Scholar was performed to identify randomized controlled trials (RCTs) according to search criteria. Search terms used included: arthroplasty, replacement, knee (Mesh), TKA, prosthesis, patella, patellar resurfacing, and patellar retaining. RCTs that compared patellar resurfacing versus unresurfaced in primary TKA were included for further analysis. Studies were evaluated using the Scottish Intercollegiate Guidelines Network assessment tool for quality and minimization of bias. Data were synthesized and meta-analysis performed. There were 4,135 TKAs (2,068 resurfaced and 2,027 unresurfaced) identified in 35 separate cohorts from 33 peer-reviewed studies. Anterior knee pain rates were significantly higher in unresurfaced knees overall (odds ratio (OR) 1.84; 95% confidence interval (CI) 1.20 to 2.83; p = 0.006) but more specifically associated with CR implants (OR 1.95; 95% CI 1.0 to 3.52; p = 0.030). There was a significantly better Knee Society function score (mean difference (MD) -1.98; 95% CI -1.1 to -2.84; p < 0.001) and Oxford Knee Score (MD -2.24; 95% CI -0.07 to -4.41; p = 0.040) for PS implants when patellar resurfacing was performed, but these differences did not exceed the minimal clinically important difference for these scores. There were no significant differences in complication rates or infection rates according to implant design. There was an overall significantly higher reoperation rate for unresurfaced TKA (OR 1.46 (95% CI 1.04 to 2.06); p = 0.030) but there was no difference between PS or CR TKA. Patellar resurfacing, when performed with CR implants, resulted in lower rates of anterior knee pain and, when used with a PS implant, yielded better knee-specific functional outcomes. Patellar resurfacing was associated with a lower risk of reoperation overall, but implant type did not influence this.

Patellar complications take a considerable amount of space after failed total knee arthroplasty (TKA). Especially pseudopatella baja is seen more often after revision knee arthroplasty cases. We present a technique where the patient has an elevated joint line as well as a dislocated patella after prior knee surgeries. Tibial tubercle osteotomy was done for the management of pseudopatella baja and the patellar component was revised along with a lateral retinacular release. The patient is now on two-year follow-up with a functional extensor mechanism and without any component failure. This technique shows an efficient and simple way of managing pseudopatella baja occurring after revision knee arthroplasty.

Posterior stabilised (PS) total knee arthroplasty (TKA) design development that focused on restoring normal knee kinematics was followed by the introduction of reason-guided motion designs. Although all PS fixed-bearing knee designs were thought to have similar kinematics, reports show they have differing incidences and magnitudes of posterior femoral rollback and axial rotation. In this retrospective comparative study between two guided-motion total knee systems, we hypothesised that kinematic pattern has an influence on clinical and functional outcomes. This study represents the continuation of a previously reported clinical and kinematics analysis. We retrospectively reviewed 347 patients treated with two different TKA designs: Scorpio NRG (Stryker Orthopedics) and Journey Bi-Cruciate Stabilised (BCS) knee system (Smith & Nephew). Two hundred and eighty-one patients were assessed clinically. Patients were divided into groups according to implanted TKA. Clinical evaluation with the Knee Injury and Osteoarthritis Outcome Score (KOOS) questionnaire was performed. Fifteen Scorpio NRG and 16 Journey BCS patients underwent video fluoroscopy during stair climbing, chair rising/sitting and step up/down at sixmonths of follow-up. At an average 29months of clinical follow-up, patients with Journey BCS TKAs reported better clinical results. Stiffness was more frequently reported in the Journey group (5.2% vs 1.2%), whereas anterior knee pain was observed in the Scorpio NRG group (1.9%) only. Both prosthetic models reported different posterior translation of the medial and lateral contact points (CP) in all analysed motor tasks during knee flexion (BCS 10-18mm; NRG Scorpio 2-3mm). Both designs produced progressive external rotation of the femoral component relative to the tibia during flexion. Journey BCS showed statistically significant better KOOS results. The higher posterior femoral rollback observed in the kinematic assessment of this design, associated with a better patellofemoral design, may be the reason for better clinical outcome. The reported cases of stiffness and anterolateral joint pain could be attributed to excessive medial and lateral tibiofemoral posterior translation. The NRG group demonstrated good axial rotation, but this was not coupled with physiological kinematic patterns. Patellofemoral pain can be explained by a less friendly femoral-groove design. TKA clinical-functional outcome and complications were highly influenced by the bearing geometry and kinematic pattern of prosthetic designs.

Bicruciate-stabilised total knee arthroplasty (BCS-TKA) uses a dual-post-cam mechanism as a substitute for the anterior cruciate ligament and posterior cruciate ligament (PCL), with the surface geometry providing additional guidance for axial rotation and posterior translation. However, the effect of weight-bearing on the kinematics of BCS-TKA has not been investigated. Therefore, the aim of this study was to clarify the effect of weight-bearing on the kinematics of BCS-TKA during high-flexion activities. The kinematics of 11 BCS-TKAs were evaluated under fluoroscopy, with two- and three-dimensional image registration, during squatting weight-bearing and active-assisted knee flexion non-weight-bearing. The following variables were measured: knee range of motion, axis of femoral rotation relative to the tibial component, anteroposterior (AP) translation of the medial contact point, kinematic path of the joint surfaces, lateral femorotibial contact point, and anterior and post-cam engagement. The weight-bearing condition did not influence the range of knee flexion, axis of femoral rotation, medial pivot pattern during early flexion, or bicondylar rollback beyond mid-flexion. With regard to AP translation, both the medial and lateral contact points had more posterior locations in weight-bearing than in non-weight-bearing at the mid-flexion angle. Anterior engagement was identified in 6/11 knees (54.5%) in weight-bearing and 4/11 knees (36.3%) in non-weight-bearing. Post-cam engagement was observed in all knees, with the angle of flexion at engagement being larger in weight-bearing than in non-weight-bearing. Although weight-bearing resulted in a posterior location of the medial and lateral contact points of the BCS-TKA design compared with non-weight-bearing in the mid-range of knee flexion, the amount of anterior translation was small overall. Therefore, BCS-TKA provides good stability during high-flexion weight-bearing activities. However, BCS-TKA is associated with high rate of the anterior engagement during early flexion. Therefore, understanding a patient's activities is an important factor when selecting the most appropriate TKA method.

Outcomes in revision knee arthroplasty: Preventing reoperation for infection Keynote lecture - BASK annual congress 2023

Which total knee arthroplasty (TKA) design represents the better solution to restore a correct knee biomechanics is still debated. The aim of this study was to compare posterior stabilized (PS) and cruciate retaining (CR) version of the same TKA design (femoral component with an anatomic sagittal radius-J-curve design) by the use of dynamic Roentgen stereophotogrammetric analysis (RSA). The hypothesis was that the two models influence differently in vivo knee kinematic. A cohort of 16 randomly selected patients was evaluated 9months after surgery: Zimmer PERSONA® was implanted, eight with CR design and eight with PS design. The kinematic evaluations were performed using a Dynamic RSA (BI-STAND DRX 2) developed in our Institute, during the execution of the sit-to-stand motor task. The motion parameters were obtained using the Grood and Suntay decomposition and the low-point kinematics methods. PS TKA lateral femoral compartment had a wider anterior translation (17 ± 2mm) than the medial one (11 ± 2mm), while the two compartments of CR TKA showed a similar anterior translation (medial: 9 ± 2mm/lateral: 11 ± 2mm). T test for comparison between CR and PS TKA of antero-posterior translation showed a statistically significant difference (p < 0.05) in the flexion range between 15° and 40°. The CR prosthesis did not anteriorly translate during flexion. The PS design translated anteriorly showing a roll-forward mechanism during extension from 80° to 18° of flexion and a posterior translation from 18° to 0°. The same significant differences (p < 0.05) between the PS and CR groups were found comparing the low-point positions of the femoral condyles in the range of flexion between 25° and 40° for the medial compartment and between 15° and 25° for the lateral compartment. Dynamic RSA was able to investigate for the first time in vivo the kinematic behaviour of PS and CR version of the same TKA J-curve design. PS type showed a medial pivot during sit-to-stand motion task, while the CR type showed a cylindrical movement. Further studies are needed to evaluate the impact of different TKA designs on clinical results. IV.

The aim of our study was to compare and contrast the effects of two types of mobile-bearing total knee arthroplasties (TKA), namely, the cruciate-retaining (CR) and posterior-stabilized (PS) TKAs, on clinical outcomes and in vivo kinematics during stair climbing. The Press-Fit Condylar Sigma rotating platform was used for both CR and PS TKAs. Patient-reported outcomes were assessed using the 2011 Knee Society Score. Quadriceps muscle strength was evaluated by isokinetic dynamometry. In vivo kinematics were evaluated using periodic sagittal plane radiographic images obtained during stair climbing to quantify anteroposterior (AP) tibiofemoral translation, implant flexion and axial rotation angles using image-matching techniques. Outcomes were evaluated in 20 TKAs, which had been undergone with clinical success, including ten knees with CR types and ten knees with PS types. There were no significant differences between the CR and PS TKA groups (p > 0.05) in isometric extensor torque (1.0 ± 0.2 and 1.1 ± 0.6Nm/kg, respectively) or patient-reported score for stair climbing function (4.0 ± 0.5 and 3.8 ± 0.9, respectively). Both types of TKAs showed stable AP translation in the mid range of knee flexion and paradoxical translation in the low range of flexion, with limited rotation, during stair climbing. There were no significant differences between the CR and PS TKA groups (P > 0.05) in anterior translation from 80° to 40° of knee flexion (4.2 ± 1.2 and 3.5 ± 1.6mm, respectively), posterior translation from 40° to 10° of knee flexion (2.3 ± 1.9 and 2.0 ± 1.5mm, respectively), and total external rotation (2.8° ± 4.9° and 0.5° ± 5.0°, respectively). Both CR and PS types of rotating platform mobile-bearing TKAs provided reproducible knee joint kinematics during stair climbing and equivalent clinical outcomes. IV.

Introduction The management of periprosthetic fractures is challenging and is guided by the configuration of the fracture, stability of implants and quality of the patient’s bone. This case report discusses the long-term fate of femoral allograft for periprosthetic fracture around a revision knee arthroplasty. Case report We present the operative technique and long-term fate of a bivalved femoral allograft used for the treatment of a periprosthetic fracture around a stemmed femoral component of a revision total knee arthroplasty (TKA) in a patient with rheumatoid arthritis and osteoporosis. Regular radiographic follow-up confirmed incorporation and docking of the allograft. A subsequent ipsilateral femoral neck fracture 4 years after allograft implantation was treated with routine total hip replacement. Conclusion The use of femoral allograft for augmenting fixation of periprosthetic fractures above a TKA is not widely reported, and, at 11 years, this case represents the longest published follow-up above a revision TKA. Our case supports the use of a bivalved total femoral allograft in the treatment of long-bone periprosthetic fractures with poor bone stock. Introduction Data from joint registries indicate an increase in the number of primary and revision knee arthroplasties being performed each year internationally, and the volume of revision knee arthroplasty being performed in the USA alone is expected to increase by 601% between 2005 and 20301. Periprosthetic supracondylar femoral fractures can occur intraoperatively and postoperatively, with an overall incidence of 0.3–2.5% above primary total knee arthroplasties (TKAs)2–7. Estimates of the incidence after revision knee arthroplasty vary greatly from 1.7% to 38%3,6–8, with most reports quoting closer to 2%. Periprosthetic femoral fractures above TKA and revision TKA have historically been associated with high complication rates when treated nonoperatively or with internal fixation4,5,9. Periprosthetic fractures are more common in the elderly population and in females7. Additional risk factors include rheumatoid arthritis, chronic steroid treatment, reduced bone stock, neurological disorders, revision surgery, notching of the anterior cortex of the femur, and in particular poor bone stock3,9–11. Primary osteopenia or secondary to stress shielding around a stemmed revision femoral component further increases the difficulty of achieving good fracture fixation by traditional methods. Whilst the introduction of locked plate technology has revolutionized surgery in the presence of osteoporotic bone12, the use of a combination of cortical femoral allograft and compression plate13 or a bivalved total femoral allograft5,14 may be indicated when a periprosthetic fracture around a well-fixed implant is complicated by deficient bone stock or significant comminution. Unfortunately, there remains insufficient evidence to strongly support the use of a single method of surgical treatment in this complex fracture group. In this case report, we aim to provide further evidence that a bivalved total femoral allograft can be successfully used in the treatment of periprosthetic femoral fractures above/around a well-fixed stemmed revision TKA and that incorporation of the graft with the host femur is possible thereby increasing the patient’s bone stock. This technique can provide a reliable long-term solution in this complex fracture group. Case report One month after primary TKA for valgus arthritis, a 60-year-old lady with polyarticular rheumatoid arthritis and severe osteoporosis re-presented with a sintering fracture of the lateral femoral condyle after a simple stumble. The femoral component was revised to an uncemented stemmed implant, and the lateral femoral condyle was reconstructed with femoral head structural allograft. Three months after discharge, she fell and sustained a spiral periprosthetic fracture around the femoral stem (Figure 1). * Corresponding author Email: gavin.macpherson@nhs.net 1 Department of Orthopaedic Surgery, The Royal Infirmary of Edinburgh, 51 Little France Crescent, Old Dalkeith Road, Edinburgh, EH16 4SA, UK 2 Stiftung Orthopadische Universitatsklinik, Schlierbacher Landstrase 200a, 69118 Heidelberg, Germany 3 Orthopadischen Klinik Paulinenhilfe, Diakonie Klinikum Stuttgart, Rosenbergstrasse 38, D-70176 Stuttgart, Germany 4 Endoklinik Hamburg, Holstenstr. 2, 22767 Hamburg, Germany

The aim of this retrospective cohort study was to investigate the reasons for total knee arthroplasty (TKA) revisions at a tertiary hospital over a four-year period. The study aimed to identify the primary causes of TKA revisions and shed light on the implications for patient care and outcomes.The study included 31 patients who underwent revisions after primary knee arthroplasty between January 2017 and December 2020. A retrospective approach was employed, utilizing medical records and radiological findings to identify the reasons for TKA revisions. The study excluded oncology patients to focus on non-oncologic indications for revision surgeries. Patient demographics, including age and gender, were recorded. Data analysis involved categorizing the reasons for revision based on clinical assessments and radiological evidence.Among the 31 patients included in the study, 9 were males and 22 were females. The age of the patients ranged from 43 to 81, with a median age of 65 and an interquartile range of 18.5. The primary reasons for TKA revisions were identified as aseptic loosening (10 cases) and prosthetic joint infection (PJI) (13 cases). Additional reasons included revision from surgitech hemicap (1 case), patella osteoarthritis (1 case), stiffness (2 cases), patella maltracking (2 cases), periprosthetic fracture (1 case), and patella resurfacing (1 case). The findings of this retrospective cohort study highlight aseptic loosening and PJI as the leading causes of TKA revisions in the examined patient population.These results emphasize the importance of optimizing surgical techniques, implant selection, and infection control measures to reduce the incidence of TKA revisions. Future research efforts should focus on preventive strategies to enhance patient outcomes and mitigate the need for revision surgeries in TKA procedures.