Undergoing Revision Total Knee Arthroplasty Research Articles

Isolated aseptic loosening in total knee arthroplasty: a comprehensive 10-year review of partial vs. total component revisions

BackgroundIn total knee arthroplasty (TKA), isolated aseptic loosening (IAL) requires the replacement of prosthetic components, with ongoing debate regarding the effectiveness of partial component revision (PCR) compared to total component revision (TCR). This study aims to compare implant survival and surgical outcomes between PCR and TCR in the context of IAL.MethodsThis retrospective study analyzed data from 285 patients who underwent revision TKA for IAL between January 2000 and December 2013. After applying exclusion criteria, 112 patients were included in the analysis—60 undergoing TCR and 52 undergoing PCR.ResultsPCR was associated with shorter operative times and hospital stays compared to TCR, alongside significant differences in the choice of revision prostheses. Although the prosthesis failure rates were comparable between the groups (13.6% for TCR and 18.33% for PCR), significant risk factors for failure were identified, including a canal filling ratio (CFR) below 0.8 and a discrepancy over 0.2 between CFR views. However, no significant differences in overall survivorship were observed between the groups.ConclusionsBoth PCR and TCR provide similar survival rates and clinical outcomes for managing IAL in TKA. PCR provides advantages in terms of surgical efficiency and patient recovery, while reducing the need for more constrained prosthetic solutions. The study identifies CFR as a critical predictor of prosthesis failure, highlighting the importance of detailed preoperative planning and implant selection. These findings contribute valuable insights for improving revision strategies in IAL, enhancing surgical outcomes in TKA.Level of evidenceIII.

Unbalanced metaphyseal fixation is associated with an increased aseptic loosening of revision total knee arthroplasty at mean 4-year follow-up.

The total number of total knee arthroplasty performed is rising, and the number of revisions is rising accordingly. Periprosthetic joint infection emerged in recent years as a leading cause of total knee revisions. Bone loss is a real challenge when facing septic knee revisions since radical debridement is crucial to overcome infection. Many devices have already demonstrated to reliably address bone loss and guarantee enhanced fixation. However, the role of balancing metaphyseal fixation and its interplay with the level of constraint has not been elucidated yet. An institutional arthroplasty registry was retrospectively reviewed looking for patients who underwent two-stage revision of the knee and metaphyseal cones implantation. Patients were divided into two groups based on the presence of cones only on one side (femoral or tibial, Group U) or both femoral and tibial side (Group B). Failure, aseptic loosening, and revision rates were compared between groups, as were values of patient-reported outcome measure. Kaplan-Meier analysis was used to assess survival of implants. A total of 65 patients were included in the analysis and were evaluated at a mean final follow-up of 4years (range, 2-7). Mean age was 67 (range, 43-81) years. Mean BMI was 27.4 (range, 20-37) kg/m2. The overall mean KSS, OKS, ROM significantly increased from baseline values to last follow-up (p < 0.001). Kaplan-Meier analysis demonstrated that patients included in Group U had a significantly lower rate of implant survival compared to those included in Group B. Patients undergoing revision total knee arthroplasty for periprosthetic infection present considerable rates of complication and failure. Management of bone loss represents a concern for the surgeon, who must achieve a stable fixation. Our study demonstrated that implants characterized by an unbalanced metaphyseal fixation are at higher risk of aseptic loosening and consequent revision, especially when coupled with hinged inserts.

Predicting prolonged length of stay following revision total knee arthroplasty: A national database analysis using machine learning models

BackgroundAs the number of revision total knee arthroplasty (TKA) continues to rise, close attention has been paid to factors influencing postoperative length of stay (LOS). The aim of this study is to develop generalizable machine learning (ML) algorithms to predict extended LOS following revision TKA using data from a national database. Methods23,656 patients undergoing revision TKA between 2013 and 2020 were identified using the American College of Surgeons National Surgical Quality Improvement Program (ACS-NSQIP) database. Patients with missing data and those undergoing re-revision or conversion from unicompartmental knee arthroplasty were excluded. Four ML algorithms were applied and evaluated based on their (1) ability to distinguish between at-risk and not-at-risk patients, (2) accuracy, (3) calibration, and (4) clinical utility. ResultsAll four ML predictive algorithms demonstrated good accuracy, calibration, clinical utility, and discrimination, with all models achieving a similar area under the curve (AUC) (AUCLR=AUCRF=AUCHGB=0.75, AUCANN=0.74). The most important predictors of prolonged LOS were found to be operative time, preoperative diagnosis of sepsis, and body mass index (BMI). ConclusionsML models developed in this study demonstrated good performance in predicting extended LOS in patients undergoing revision TKA. Our findings highlight the importance of utilizing nationally representative patient data for model development. Prolonged operative time, preoperative sepsis, BMI, and elevated preoperative serum creatinine and BUN were noted to be significant predictors of prolonged LOS. Knowledge of these associations may aid with patient-specific preoperative planning, discharge planning, patient counseling, and cost containment with revision TKA.

A comparison between 3D printed models and standard 2D planning in the use of metal block augments in revision knee arthroplasty.

The study focused on the ability to predict the need and size of femoral and tibial augmentation using standard two-dimensional (2D) templates and models created with three-dimensional (3D) printing in surgical planning. This observational cohort study included 28 consecutive patients (22 females, 6 males; mean age: 71±7.3 years; range, 54 to 82 years) with periprosthetic joint infection recruited between March 2021 and September 2023 undergoing revision total knee arthroplasty revision (TKA). Standard planning was made using calibrated X-ray images. The 3D planning started with computed tomography scans to generate a 3D template of the distal femur and proximal tibia. The model was exported to a 3D printer to produce a patient-specific phantom. The surgery was then simulated on the 3D phantom using revision knee arthroplasty instrumentation to evaluate the appropriate augmentation to use until a correct alignment was obtained. Three-dimensional planning predicted the need for femoral and tibial augments in 22 (78.6%) cases at both the tibial and femoral components, while 2D planning correctly predicted the need for augmentation in 17 (60.7%) for the tibial side and 18 (64.3%) for the femoral side. The Cohen's kappa demonstrated a significant agreement between the 3D planning for the femoral metal block and the intraoperative requirement (kappa=0.553), whereas 2D planning showed only nonsignificant poor agreement (kappa=0.083). In contrast, the agreement between 2D or 3D preoperative planning for tibial augment and the intraoperative requirement was nonsignificant (kappa=0.130 and kappa=0.158, respectively). On the femoral side, 2D planning showed only a fair nonsignificant correlation (r=0.35, p=0.069), whereas 3D planning exhibited substantial agreement with the actual thickness of the implanted augment (r=0.65, p<0.001). On the tibial side, 3D and 2D planning showed substantial agreement with the actual size of implanted augments (3D planning, r=0.73, p<0.001; 2D planning, r=0.69, p<0.001). Prediction based on 3D computed tomography segmentation showed significant agreement with the intraoperative need for augmentations in revision TKA. The results suggest that planning with 3D printed models represents a stronger aid in this kind of surgery rather than standard 2D planning, providing greater accuracy in the prediction of the required augmentation in revision TKA.

Impact of systemic lupus erythematosus (SLE) on outcomes following aseptic and septic revision total knee arthroplasty: an analysis of the 2005-2018 nationwide inpatient sample.

Systemic lupus erythematosus (SLE) can adversely affect surgical outcomes, and the impact on revision total knee arthroplasty (TKA) outcomes is unclear. This study aimed to explore the impact of SLE on in-patient outcomes of revision TKA. The Nationwide Inpatient Sample (NIS) database from 2005 to 2018 was searched for patients aged ≥ 18years old who received revision TKA. Patients with and without SLE were propensity score matched (PSM) at a 1:4 ratio. Associations between SLE and in-hospital outcomes were examined using regression analyses. The study included 133,054 patients, with 794 having SLE. After 1:4 PSM, data of 3,970 patients were analyzed (SLE, 794; non-SLE, 3,176). Multivariate-adjusted analyses revealed that SLE patients had a significantly higher risk of postoperative complications (adjusted odds ratio [aOR] = 1.23, 95% confidence interval [CI]: 1.05-1.44, p = 0.011), non-routine discharge (aOR = 1.22, 95% CI: 1.02-1.46, p = 0.028), major blood loss (aOR = 1.19), respiratory failure/mechanical ventilation (aOR = 1.79), acute kidney injury (AKI) (aOR = 1.47), and wound dehiscence (aOR = 2.09). SLE patients also had a longer length of hospital stay (aBeta = 0.31) and greater total hospital costs (aBeta = 6.35) compared to non-SLE patients. Among those with aseptic failure, SLE patients had a significantly higher risk of postoperative complications (aOR = 1.23) and non-routine discharge (aOR = 1.36). SLE is independently associated with worse in-hospital outcomes in patients undergoing revision TKA. This study highlights the importance of heightened vigilance and tailored perioperative management for patients undergoing major surgeries in the background of SLE. Key Points • SLE significantly increases the risk of non-routine discharge, major blood loss, respiratory failure, acute kidney injury, and wound dehiscence, in patients undergoing aseptic and septic revision TKA. • Patients with SLE experience longer hospital stays and higher hospital costs compared to those without SLE. • The study's findings highlight the necessity for healthcare providers to consider the presence of SLE as a critical factor in preoperative planning and postoperative care to improve outcomes in revision TKA patients.

Promising short-term outcomes of free-hand burring technique to implant second-generation metaphyseal cone in Asian knees – a case series

BackgroundThe second-generation metaphyseal cone was useful in managing bone defects in revision knee arthroplasty. However, due to the anatomical constraints in Asian osteometry, the authors utilized a novel free-hand burring technique instead of cannulated reaming for bone preparation. We reported the short-term outcomes of our surgical techniques specific to Asian osteometry.MethodsWe conducted a case series by consecutively recruiting 13 female and 12 male patients (involving 25 knees), with a mean age of 71 years (range, 54–88 years). The patients underwent revision total knee arthroplasty during the period from April 2017 to June 2022. Twenty-three tibial cones and 4 femoral cones using free-hand burring technique were implanted. The mean follow-up duration was 51 months (range 18–80 months). Due to the relatively small bone size and meta-diaphyseal center mismatch in the Asian knees, the free-hand burring technique instead of the cannulated reaming technique was adopted in preparing for cone implantation. The clinical outcomes were knee ranges of motion, the Knee Society Knee scores (KSS), end-of-stem pain, infection, and the need for revision surgery. The radiological outcomes included osteointegration, fracture, and loosening.ResultsMean knee range of motion improved from 83 degrees (range 0°–120°) preoperatively to 106 degrees (range 60°–125°) postoperatively (P < 0.001). Mean KSS improved significantly from 29 (range 0–70) to 69 (range 5–100) (P < 0.001). All cones were osteointegrated. One case had transient end-of-stem pain, two developed intraoperative minor femoral fractures and one suffered from recurrent infection that did not require cone revision. Cone revision-free survivorship was 100%. There was no aseptic loosening.ConclusionsThe second-generation cone implanted with free-hand burring bone preparation yielded promising short-term outcomes in Asian knees.

Comparison of Novel 3D-printed Stepped Porous Metal Cones and Metaphyseal Sleeves for Reconstruction of Severe Knee Bone Defects: Short-term Clinical Outcomes.

Both porous metal cones and metaphyseal sleeves are excellent implants for reconstructing severe bone defects in the knee joint, but they both exhibit design limitations. The porous metal cone, especially, has significant room for improvement in its shape design. The existing porous metal cones often feature a conical external surface with a relatively small taper, potentially compromising both rotational and axial stability. To improve both axial and rotational stability in porous metal cones, we developed a 3D-printed stepped porous metal cone. This study aimed to assess the short-term clinical outcome of the 3D-printed stepped porous metal cone and to compare it with the clinical outcome of patients who underwent revision total knee arthroplasty (rTKA) with the metaphyseal sleeves during the same period. Patients who underwent total knee arthroplasty revision with metaphyseal bone defect reconstruction from 2019 to 2021 were retrospectively analyzed. A total of 61 patients were enrolled in the study, including 15 patients using 3D-printed stepped porous metal cones and 46 patients using metaphyseal metal sleeves. Thirty patients using metaphyseal sleeves were screened by propensity score matching method and compared with those using stepped cones. Analysis included the American Knee Society Score, the Hospital for Special Surgery knee score, the Western Ontario and McMaster Universities Arthritis index, the Short Form 12 (SF-12) health survey, and radiographic assessment with a mean follow-up of 28.5 ± 8.3 months. To conduct comparative analyses, unpaired Student's t-tests were employed for continuous variables, while categorical variables were analyzed using the appropriate Fisher exact or chi-squared test. In this study, the survival rates of both the stepped cone and metaphyseal sleeve were 100%. There was no statistically significant difference in postoperative knee function scores between the two groups (p > 0.05). However, patients in the cone group had significantly higher mental component summary scores on the SF-12 scale (p < 0.05) and higher increases in mean postoperative physical component summary scores than patients in the sleeve group (p < 0.05). In addition, patients in the cone group experienced fewer intraoperative and postoperative complications compared to the sleeve group. The 3D-printed stepped porous metal cone can effectively reconstruct bone defects in complex rTKA and provide satisfactory early clinical and radiographic results. The 3D-printed stepped cone provides a more stable structure similar to the sleeve while maintaining the original benefits of the cone making it a promising choice for rTKA.

Characterizing the Magnitude and Risk Factors of Functional and Anatomic Limb Lengthening in Patients Undergoing Revision Total Knee Arthroplasty

BackgroundIn revision total knee arthroplasty (TKA), there is little information on the magnitude of potential limb lengthening, risk factors for lengthening, or its impact on patient-reported outcome measures. We aimed to quantify limb length alteration during revision TKA and assess risk factors for lengthening. MethodsWe identified 150 patients over a 3-year period who underwent revision TKA and had preoperative and postoperative EOS hip-to-ankle standing radiographs. The average patient age was 64 years, 51% were women; 68% had a preoperative varus deformity and 21% had a preoperative valgus deformity. Outcomes assessed included change in functional and anatomic limb length, risk factors for lengthening, and clinical outcome scores, including the Knee Osteoarthritis Outcome Score Joint Replacement, and the Veterans RAND 12-item Physical and Mental Scores. ResultsThere were 124 patients (83%) who had functional limb lengthening, and 108 patients (72%) had anatomic limb lengthening. Patients had an average functional limb lengthening of 7 mm (range, −22 to 35) and an average anatomic limb lengthening of 5 mm (range, −16 to 31). Patients undergoing revision for instability experienced significantly greater anatomic lengthening (7.6 versus 4.6, P = .047). Patients who had ≥ 10° of deformity were more likely to be functionally lengthened (91 versus 79%) and had significantly greater average functional lengthening (12 versus 6 mm; P = .003). There was no significant change in clinical outcome scores at 6 weeks and 1 year for patients lengthened ≥ 5 or 10 mm compared to those not lengthened as substantially. ConclusionsThere is major potential for functional and anatomic limb lengthening following revision TKA, with greater preoperative deformity and revision for instability being risk factors for lengthening.

Complex periprosthetic wound coverage in patients undergoing revision total knee arthroplasty: a single plastic surgeon study.

Options for soft tissue coverage in revision total knee arthroplasty (rTKA) range from primary wound closure to complex muscle flap reconstructions. The purpose of this study was to investigate the institutional experience of wound coverage options for complex soft tissue defects in rTKA. 77 patients undergoing rTKA with complex wound closure by a single plastic surgeon were retrospectively reviewed. The average follow-up was 30.1 months. In 18 (23.4%) patients, an intraoperative decision for primary closure was made. Fifty-nine patients (76.6%) received either a local fasciocutaneous (N = 18), a medial gastrocnemius (N = 37), a free latissimus dorsi (N = 3) or a lateral gastrocnemius flap (N = 1). Revision-free survival and complication rates were assessed and risk factors were analyzed with Cox-regression analysis. Medial gastrocnemius flaps had significant lower cumulative revision-free survival rates than local fasciocutaneous flaps (P = 0.021) and primary closures (P < 0.001) (42.5% vs. 71.5% vs. 100%,respectively). Comparing the most common complex closure procedures medial gastrocnemius flaps had the highest rate of prolonged wound healing (29.7%) and infection/reinfection (40.5%). Infection-associated flap procedures had significant lower cumulative revision-free survival rates (30.5%) than non-infection associated flap procedures (62.8%,P = 0.047). A history of more than two prior surgeries (HR = 6.11,P < 0.001) and an age ≥ 65 years (HR = 0.30,P = 0.018) significantly increased the risk of revision. The results of this study indicate that primary closure -if possible- should be preferred to early proactive muscle flap coverage. Even in the hands of an experienced plastic surgeon muscle flaps have high revision and complication rates. The study highlights the need to clarify flap indications and to investigate alternative approaches.

Commercial Synovial Antigen Testing is Inferior to Traditional Culture for the Diagnosis of Periprosthetic Joint Infection in Patients Undergoing Revision Total Knee Arthroplasty

BackgroundDespite its limitations, a culture remains the “gold standard” for pathogen identification in patients who have periprosthetic joint infection (PJI). Recently, a synovial fluid antigen test has been introduced by a commercial entity. The purpose of this multicenter study was to determine the accuracy of the antigen test in the diagnosis of PJI. MethodsThis retrospective study identified 613 patients undergoing revision total knee arthroplasty who had undergone preoperative synovial fluid analysis. A PJI was defined using the 2018 International Consensus Meeting (ICM) criteria. Patients who had an extended period (> 180 days) from aspiration to revision procedure (n = 62), those presenting within 90 days of their index arthroplasty procedure (n = 17), and patients who had an inconclusive ICM score (n = 8) were excluded. Using receiver operator characteristic curve analyses, we examined the utility of the microbial identification (MID) antigen test and any positive culture (either preoperative or intraoperative) in the diagnosis of PJI. ResultsA total of 526 patients were included. Of these, 125 (23.8%) were ICM positive and 401 (76.2%) were ICM negative. Culture demonstrated an area under the curve (AUC) of 0.864, sensitivity of 75.2%, and specificity of 97.5%. On the other hand, the MID test exhibited an AUC of 0.802, sensitivity of 61.6%, and specificity of 98.8%. The AUC of culture was significantly higher than that of the MID test (P = .037). The MID test was positive in 41.9% of culture-negative PJI cases. We also observed a high rate of discordance (29.7%) when both culture and the MID test were positive in the ICM-positive group. ConclusionsSynovial fluid antigen testing does not provide additional clinical benefit when compared to traditional cultures for the diagnosis of PJI. The antigen test had low sensitivity in the diagnosis of PJI and a relatively high rate of discordance with culture. Level of EvidenceLevel III.

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

The mean age of patients undergoing total knee arthroplasty (TKA) has reduced with time. Younger patients have increased expectations following TKA. Aseptic loosening of the tibial component is the most common cause of failure of TKA in the UK. Interest in cementless TKA has re-emerged due to its encouraging results in the younger patient population. We review a large series of tantalum trabecular metal cementless implants in patients who are at the highest risk of revision surgery. A total of 454 consecutive patients who underwent cementless TKA between August 2004 and December 2021 were reviewed. The mean follow-up was ten years. Plain radiographs were analyzed for radiolucent lines. Patients who underwent revision TKA were recorded, and the cause for revision was determined. Data from the National Joint Registry for England, Wales, Northern Island, the Isle of Man and the States of Guernsey (NJR) were compared with our series. No patients in our series had evidence of radiolucent lines on their latest radiological assessment. Only eight patients out of 454 required revision arthroplasty, and none of these revisions were indicated for aseptic loosening of the tibial baseplate. When compared to data from the NJR annual report, Kaplan-Meier estimates from our series (2.94 (95% confidence interval (CI) 1.24 to 5.87)) show a significant reduction in cumulative estimates of revision compared to all cemented (4.82 (95% CI 4.69 to 4.96)) or cementless TKA (5.65 (95% CI 5.23 to 6.10)). Our data (2.94 (95% CI 1.24 to 5.87)) also show lower cumulative revision rates compared to the most popular implant (PFC Sigma Cemented Knee implant fixation, 4.03 (95% CI 3.75 to 4.33)). The prosthesis time revision rate (PTIR) estimates for our series (2.07 (95% CI 0.95 to 3.83)) were lower than those of cemented cases (4.53 (95% CI 4.49 to 4.57)) from NJR. The NexGen trabecular (tantalum) cementless implant has lower revision rates in our series compared to all cemented implants and other types of cementless implants, and its use in younger patients should be encouraged.

A Comparison Between Polyethylene Exchange and Full Revision for Arthrofibrosis Following Total Knee Arthroplasty

BackgroundArthrofibrosis is a debilitating postoperative complication and a major cause of patient dissatisfaction following total knee arthroplasty (TKA). There is no consensus regarding the optimal treatment for stiffness after TKA. For cases not amenable to manipulation under anesthesia (MUA), one component or full revision are both suitable options. In a value-based healthcare era, maximizing cost-effectiveness with optimized clinical outcomes for patients remains the ultimate goal. As such, we compared (1) Knee Injury and Osteoarthritis Outcome Scores for Joint Replacement (KOOS, JR), (2) range of motion (ROM), as well as (3) complication rates, including MUA and lysis of adhesions (LOA), between polyethylene exchange and full component revision for TKA arthrofibrosis. MethodsPatients were queried from an institutional database who underwent revision TKA for arthrofibrosis between January 1, 2015, and April 31, 2021. There were 33 patients who underwent full revision and 16 patients who underwent polyethylene exchange. Demographics and baseline characteristics between the cohorts were analyzed. Postoperative outcomes included MUA, LOA, and re-revision rates as well as KOOS, JR, and extension and flexion ROM at a mean follow-up of 3.8 years. Baseline comorbidities, including age, body mass index, alcohol use, tobacco use, and diabetes, were comparable between the full revision and polyethylene exchange revision cohorts (P > .05). The one and full component revisions had similar preoperative KOOS, JR (43 versus 42, P = .85), and flexion (81 versus 82 degrees, P = .80) versus extension (11 versus 11 degrees, P = .87) ROM. ResultsThe full component revision had higher KOOS, JR (65 versus 55, P = .04), and flexion (102 versus 92 degrees, P = .02), but similar extension (3 versus 3 degrees, P = .80) ROM at final follow-up compared to the polyethylene exchange revision, respectively. The MUA (18.2 versus 18.8%, P = .96) and LOA (2.0 versus 0.0%, P = .32) rates were similar between full component and polyethylene exchange revisions. There was one re-revision (3.0%) for the cohort of patients who initially underwent full revision. There were four full re-revisions (25.0%) and two polyethylene exchange re-revisions (12.5%) performed in the cohort of patients who initially underwent a polyethylene exchange revision. ConclusionsThe full component revision for stiffness after TKA showed favorable KOOS, JR, ROM, and outcomes in comparison to the polyethylene exchange revision. While the optimal treatment for stiffness after TKA is without consensus, this study supports the use of the full component revision when applied to the institutional population at hand. It is imperative that homogeneity exists in preoperative definitions, preoperative baseline patient demographics, ROM and function levels, outcome measures, and preoperative indications, as well as the inclusion of clinical data that assesses complete exchange, single exchange, and tibial insert exchange.

Clinical Outcomes of Isolated Polyethylene Exchange Versus Full Component Revision for the Management of Instability Following Total Knee Arthroplasty

BackgroundInstability following total knee arthroplasty (TKA) is a common cause for revision. Isolated polyethylene exchange (IPE) can be performed to increase knee joint stability, but results have been mixed. The purpose of this study was to compare the survivorship and patient-reported outcomes of patients undergoing revision TKA for instability with IPE versus full component revision. MethodsWe reviewed 280 primary TKAs undergoing revision TKA for instability. There were 181 knees that underwent revision with IPE, compared to 99 knees treated with full component revision. The mean follow-up was 32.8 months (range, 24.8 to 82.5). Patient demographics, radiographic parameters, prosthesis constraints, reoperations for instability, and patient-reported outcomes were compared. ResultsThe survivorship for instability was significantly higher at 2 years (99 versus 92%, P = .024) and 5 years (94 versus 84%, P = .024) for patients undergoing full component revision. Although there was no difference in Knee Injury and Osteoarthritis Outcome Score for Joint Replacements and Veterans RAND 12 physical component scores between the 2 groups at 6 weeks, 1 year, and 2 years after surgery, full revision patients reported greater pain relief (P = .006) and greater improvements in Veterans RAND 12 physical component scores (P = .027) at 1 year and Knee Injury and Osteoarthritis Outcome Score for Joint Replacements scores at 2 years (P = .017) compared to IPE patients. Men were associated with an increased risk for recurrent instability following IPE (hazard ratio 3.3, 95% confidence interval: [1.0 to 10.6]). ConclusionsIsolated polyethylene exchange was not as reliable or durable compared to full component revision for the management of postoperative instability. These procedures should only be reserved in cases with competent collaterals and when component position, offset, and rotation are optimized.

Porous Tantalum Metaphyseal Cones for Severe Femoral and Tibial Bone Defects in Revision Total Knee Arthroplasty are Reliable for Fixation at Mean 5-Year Follow-Up

BackgroundPorous tantalum metaphyseal cones may facilitate reconstructions of severe bone defects during revision total knee arthroplasty (TKA), but there remains a paucity of data on their outcomes at mean 5 years of follow-up. This study reports the component survivorship, patient satisfaction, functional outcomes, radiographic osseointegration, and complications of revision TKA with porous tantalum metaphyseal cones at mid-term (mean 5-year) follow-up. MethodsThis study included 152 patients who had a mean age of 66 years (range, 33 to 86 years) undergoing revision TKA with porous tantalum metaphyseal cones. Indications for surgery included aseptic loosening (n = 87, 57.3%), second-stage reimplantation for infection (n = 42, 27.6%), osteolysis with well-fixed components (n = 20, 13.2%), and periprosthetic fracture (n = 3, 2.0%). Component survivorship, clinical outcomes, radiographic outcomes, and any complications were recorded. The mean follow-up time was 5.6 years (range, 2.2 to 13.7). ResultsSurvivorship was 100% when the end point was revision of the metaphyseal cone (no cones were revised) and 83.8% (95% confidence interval: 77.9 to 90.2%) when the end point was reoperation for any reason at 5-year follow-up. Reoperations were performed for infection (n = 10), instability (n = 4), periprosthetic fracture (n = 2), and quadriceps rupture/dehiscence (n = 3). The mean patient satisfaction score was 78.8 ± 11.3 and the mean Forgotten Joint Score was 62.2 ± 16.7 at the final follow-up. The preoperative median University of California at Los Angeles score improved from 2 (interquartile range 2 to 3) to 6 points (interquartile range 5 to 6) (P < .001), and the preoperative Oxford knee score improved from 15.2 ± 3.8 to 39.4 ± 5.1 points (P < .001) at the final follow-up. All metaphyseal cones showed radiographic evidence of osteointegration without any subsidence or loosening. ConclusionsPorous tantalum metaphyseal cones enabled robust reconstructions of severe femoral and tibial bone defects during revision TKA. These reconstructions were associated with excellent survivorship, improvements in functional outcomes, and reproducible radiographic osseointegration at mean 5-year follow-up. The most common reasons for reoperation were infection and instability.

Incidence of patella baja and pseudopatella baja in aseptic revision total knee arthroplasty.

There are two variants regarding the low location of the patella in relation to the tibio-femoral joint line: patella baja (PB) and pseudo-patella baja (PPB). The purpose of this study is to investigate the incidence of PB and PPB in a cohort of patients that underwent revision total knee arthroplasty (rTKA) for aseptic reasons and describe any differences in each group's ROM. This retrospective study included 114 patients that underwent aseptic revision TKA surgery between 2017 and 2022. Patients were revised either for stiffness (Group 1) or aseptic loosening/instability (Group 2). The Insall-Salvati ratio (ISR) and Blackburne-Peel ratio (BPR) were used to evaluate the patellar position. ISR < 0.8 defined PB, while cases with ISR ≥ 0.8 and BPI < 0.54 were defined as PPB. ROM was measured and a subanalysis was conducted to investigate the progression of the values of ISR and BPR. 55 patients comprised Group 1, and 59 patients comprised Group 2. Overall, 13 cases (11.4%) had PB before rTKA and 24 (21%) had PB after rTKA. Cases with PPB were 13 (11.4%) before and 34 (29.9%) after rTKA. Group 1 patients presented with more PB before and after rTKA (12.8% vs 10.2% and 27.3% vs 15.2% respectively). However, after rTKA Group 1 patients presented with less PPB (20%) compared to Group 2 (39%) (p = 0.02). In Group 1, patients with PPB after rTKA had less ROM compared to those without PPB [83.2 (± 21.9) vs 102.1 (± 19.9) (p = 0.025)]. The subanalysis (69 patients) showed a statistically significant decrease in ISR before and after rTKA (p = 0.041), and from the native knee to post-rTKA (p = 0.001). There was a statistically significant decrease in BPR before and after rTKA (p = 0.001) and from the native knee to both pre- and post-rTKA (p < 001). After undergoing rTKA, the incidences of both patella baja (PB) and pseudo-patella baja (PPB) increased. Stiffness in the knee was associated with a higher incidence of PB, while non-stiffness cases showed a significantly higher incidence of PPB. Patients with stiff knees and PPB after rTKA experienced a significant reduction in range of motion (ROM). Additionally, the study revealed a noteworthy decrease in ISR and BPR with each subsequent surgery. This information is crucial for healthcare providers, as it sheds light on potential risks and outcomes of rTKA, allowing for improved patient management and surgical decision-making. III.

Good Short-Term Survivorship of Constrained Condylar Revision Knee Implants With Medial Pivot Kinematics: A Level IV Retrospective Study

BackgroundThe need for revision total knee arthroplasty surgery is increasing worldwide, and, in many cases, a constrained implant is required to provide joint stability. The purpose of this study was to examine the early loosening and functional outcome of a novel constrained condylar (CCK) revision total knee system designed to have medial pivot (MP) kinematics. MethodsA retrospective cohort study was performed, collecting clinical data from all patients who underwent revision total knee arthroplasty using a novel MP CCK system with a minimum four-year clinical follow-up. Patient demographics, survivorship, complications, and Forgotten Joint Score were analyzed based upon chart review. ResultsThere were 49 patients available for follow-up, who had a 100% survivorship free of aseptic loosening. All-cause revision survivorship was 92%. There were 4 patients who subsequently underwent rerevision. The causes for rerevision included periprosthetic joint infection in 2 patients, coronal plane instability in one patient, and a traumatic knee dislocation in one patient. There were 45 patients who completed the Forgotten Joint Score, who had an average of 49.8 (± 32.8, range 6.25 to 100). ConclusionsAt 4 years, mid-term follow-up, this novel CCK revision total knee system designed to have MP kinematics had good patient-reported outcomes with no revision for aseptic loosening. Future studies should evaluate the mid- and long-term survivorship of this innovative implant.

Outcomes of Metaphyseal Cones and Stem Fixation Following Rotating Hinge in Complex Primary and Revision Total Knee Arthroplasty

BackgroundAlthough hinged prostheses have been used successfully in complex revision total knee arthroplasty (TKA), concerns exist regarding early failure due to aseptic loosening and other mechanical complications. The use of metaphyseal cones and hybrid cement fixation have been studied in unlinked constrained primary or revision TKA, but their impact on the survivorship of hinged prostheses has yet to be investigated. MethodsWe identified a consecutive series of 164 hinged prostheses and collected data on demographics, indications, complications, and re-revisions in patients who had fully cemented versus hybrid stems, with and without metaphyseal cones. A multivariate analysis was performed to identify independent variables associated with re-revision as the primary end point. ResultsIn total, 84 patients (51.2%) had fully cemented stems, and 80 patients (48.8%) had hybrid stems. Cones were used in 73 patients (44.5%). At a mean follow-up of 3.4 ± 2.2 years, 42 patients underwent re-revision (25.8%), most commonly for infection (12.2%), followed by loosening (6.7%) and periprosthetic fracture (3.7%). Patients who had fully cemented stems had lower re-revision rates than hybrid fixation constructs (19 versus 26%, P = .043). Using multivariable regression, a construct with hybrid fixation with cones (odds ratio = 2.39; P = .037) was an independent risk factor for failure. Utilization of cones alone did not have an effect on re-revision rates at 3.4-year follow-up. ConclusionsWhile we found no difference with the use of cones, patients undergoing revision TKA with a hinge prosthesis and fully cemented stems had better overall survivorship than hybrid stems.

BORS/BJR TRAVELLING FELLOWSHIP ABSTRACT: THE EFFECT OF INCREASING BONE LOSS ON THE PRIMARY STABILITY OF METAPHYSEAL SLEEVES IN THE PROXIMAL TIBIA. AN EXPERIMENTAL STUDY USING SAWBONE TIBIAS

AbstractApproximately 20% of primary and revision Total Knee Arthroplasty (TKA) patients require multiple revisions, which are associated with poor survivorship, with worsening outcomes for subsequent revisions. For revision surgery, either endoprosthetic replacements or metaphyseal sleeves can be used for the repair, however, in cases of severe defects that are deemed “too severe” for reconstruction, endoprosthetic replacement of the affected area is recommended. However, endoprosthetic replacements have been associated with high complication rates (high incidence rates of prosthetic joint infection), while metaphyseal sleeves have a more acceptable complication profile and are therefore preferred. Despite this, no guidance exists as to the maximal limit of bone loss, which is acceptable for the use of metaphyseal sleeves to ensure sufficient axial and rotational stability. Therefore, this study assessed the effect of increasing bone loss on the primary stability of the metaphyseal sleeve in the proximal tibia to determine the maximal bone loss that retains axial and rotational stability comparable to a no defect control.Methodsto determine the pattern of bone loss and the average defect size that corresponds to the clinically defined defect sizes of small, medium and large defects, a series of pre-operative x-rays of patients with who underwent revision TKA were retrospectively analysed. Ten tibiae sawbones were used for the experiment. To prepare the bones, the joint surface was resected the typical resection depth required during a primary TKA (10mm). Each tibia was secured distally in a metal pot with perpendicular screws to ensure rotational and axial fixation to the testing machine. Based on X-ray findings, a fine guide wire was placed 5mm below the cut joint surface in the most medial region of the plateau. Core drills (15mm, 25mm and 35mm) corresponding to small, medium and large defects were passed over the guide wire allowing to act at the centre point, before the bone defect was created. The test was carried out on a control specimen with no defect, and subsequently on a Sawbone with a small, medium or large defect. Sleeves were inserted using the published operative technique, by trained individual using standard instruments supplied by the manufacturers. Standard axial pull-out (0 – 10mm) force and torque (0 – 30°) tests were carried out, recording the force (N) vs. displacement (mm) curves.ResultsA circular defect pattern was identified across all defects, with the centre of the defect located 5mm below the medial tibial base plate, and as medial as possible. Unlike with large defects, small and medium sized defects reduced the pull-out force and torque at the bone-implant interface, however, these reductions were not statistically significant when compared to no bony defect.ConclusionsThis experimental study demonstrated that up to 35mm radial defects may be an acceptable “critical limit” for bone loss below which metaphyseal sleeve use may still be appropriate. Further clinical assessment may help to confirm the findings of this experimental study. This study is the first in the literature to aim to quantify “critical bone loss” limit in the tibia for revision knee arthroplasty.Declaration of Interest(a) fully declare any financial or other potential conflict of interest

Mid term outcomes of a novel metaphyseal porous titanium cone in revision total knee arthroplasty

IntroductionBone loss is present in all revision total knee arthroplasties. Metaphyseal cones allow surgeons to negotiate loss of femoral and tibial bone stock while obtaining stable bony fixation. This study examines the mid-term functional and radiographic outcomes in patients undergoing revision total knee arthroplasty (rTKA) utilizing a novel metaphyseal cone system. MethodsThis multicenter retrospective study examined all patients who received a porous, titanium tibial or femoral cone at four academic urban tertiary care institutions and presented for a minimum two-year follow-up. Patient demographics, indications for revision surgery, knee range-of-motion (ROM), re-revision rates, radiographic measurements, bone defect per AORI classification, and implant osseointegration were evaluated according to the Knee Society total knee arthroplasty (TKA) radiographic evaluation system. ResultsOne-hundred and four patients received 128 cone implants (84 tibial, 44 femoral cones; 24 patients with simultaneous ipsilateral tibial and femoral cones; 104 rTKA) with mean follow-up of 32.75 ± 6.54 months. The pre-operative main revision indications were aseptic loosening 36 (34.61 %), periprosthetic infection (PJI) 23 (22.11 %) and instability 18 (17.3 %). Thirteen rTKA underwent re-revision surgery: 3 for acute PJI, 4 for chronic PJI, 5 for instability, and 1 for mechanical failure of a hinged system. At most recent radiographic follow-up available, all unrevised cones had evidence of osteointegration and no visible implant migration.All-cause re-operation free survivorship was 87.5 % (91/104), and all-cause cone implant survivorship was 96.09 % (123/128 cones) at 2-year follow-up. ConclusionThis study demonstrates excellent mid-term outcomes of a novel porous, titanium metaphyseal cone in patients with large bone defects undergoing complex revision TKA. Level of evidenceIV, case series.

Polyethylene exchange versus full component revision for arthrofibrosis following total knee arthroplasty: A retrospective cohort analysis

IntroductionArthrofibrosis occurs in up to 10% of patients who undergo total knee arthroplasty (TKA). For cases that are not amenable to manipulation under anesthesia (MUA), there is little consensus on how many components should be revised. We compared outcomes of polyethylene exchanges, when doing lysis of adhesions (LOA) versus full component revision. Specifically, we assessed: (1) re-operation rates at one and two years; (2) rates of surgical complications at one year; and (3) associated risk factors for requiring a LOA. MethodsA database queried all patients who underwent revision TKA for arthrofibrosis. A total of 2410 patients were identified, 1120 (46.5%) of which underwent all-component knee revision, while the remaining 1290 (53.5%) underwent polyethylene spacer revision. Multivariate logistic regressions assessed re-operation rates and risk factors for requiring LOA. ResultsThe incidence and odds of re-operation within one year following polyethylene exchange was not significantly different than full component revision (10.9 versus 12.9%, odds ratio (OR) 0.83, 95% confidence interval (CI) [0.64–1.06], p = 0.145). However, the adjusted models for re-operation within one- and two-years following LOA in the form of polyethylene exchange revision was significantly higher than the full component revision cohort (OR 1.52 CI [1.07–2.17], p = 0.022 and OR 1.44 CI [1.06–1.97] p = 0.022). Risk factors associated with the need for lysis of adhesions included age less than 60 years, depression, fibromyalgia, and anxiety. ConclusionsFull component revision TKA for arthrofibrosis was associated with lower two-year re-operation rate than polyethylene exchange. Risk factors for LOA include younger age and fibromyalgia.