Increased Risk of Infection in Unicompartmental Knee Arthroplasty Conversions Compared to Revision Primary Total Knee Arthroplasty in the Aseptic Setting: Answering the International Consensus Meeting Call for Database Research.

Divergent Dynamics: Unicompartmental Knee Arthroplasty Enables Greater Propulsive Joint Moments Compared To Total Knee Arthroplasty.

Disease progression in the untreated compartment is the leading cause for reoperation following unicompartmental knee arthroplasty (UKA). A less-invasive alternative to total knee arthroplasty (TKA) conversion is the addition of a second UKA. The study assessed survival, functional, and radiological outcomes after two-staged bicompartmental UKA. A retrospective analysis was performed on 102 knees (98 patients, mean age 73.7 years) who received an additional medial (n = 29) or lateral UKA (n = 73) between 2016 and 2025 with a minimum follow-up of 1 year. Primary outcomes were cumulative revision rates for (1) any reoperation and (2) implant revision. Functional outcomes included the Oxford Knee Score (OKS) and UCLA (University of California, Los Angeles) Activity Score. Radiographic assessment included measurement of the hip-knee-ankle angle (HKAA). The mean follow-up was 4.0 years (SD 2.1). At 9 years, cumulative survival rate was 84.3% (95% CI: 0.763-0.923) for any reoperation and 89.3% (95% CI: 0.822-0.964) for implant revision. There were nine implant revisions (8.8%), most commonly due to medial mobile-bearing dislocation (44.4%). In 50%, implant revision to TKA was performed using primary non-modular components. Mean postoperative OKS and UCLA scores were 40.4 (SD 8.0) and 5.5 (SD 1.7), respectively. Medial osteonecrosis (ON) following primary lateral UKA accounted for 38% (11/29) of all indications for an additional medial UKA, and was associated with greater HKAA correction following prior lateral UKA. Two-staged bicompartmental UKA is a viable less-invasive alternative to TKA conversion for patients with disease progression or ON after primary UKA. This approach demonstrates excellent mid-term functional outcomes and satisfactory implant survivorship, providing valuable evidence to support its role as a contemporary revision option Fixed-bearing implants for additional medial UKA are advised to eliminate the risk of bearing dislocations. In the absence of major complications, conversion to non-modular TKA components is feasible. Level IV.

Preoperative Knee Bone Marrow Edema Is Associated With Poor Clinical Outcomes Following Posterior Medial Meniscal Root Repair.

Do Patients Undergoing Unicompartmental Knee Arthroplasty Who Fail to Achieve Minimal Clinically Important Difference Have Higher Rates of Conversion to Total Knee Arthroplasty?

The purpose of this study was to evaluate the efficacy of conventional and minimally invasive approaches to total knee arthroplasty (TKA) by comparing the pain score, range of motion (ROM), and adverse effects. It was hypothesized that minimally invasive approaches would lead to superior outcomes. Randomized control trials comparing various approaches to TKA were identified in various literature databases from conception through December 31, 2022. A network meta-analysis (NMA) of relevant literature was performed to investigate which approaches showed better outcomes. In total, 42 studies were included in this study. The main finding of this NMA was that the minimally invasive midvastus (MMV) approach led to better outcomes in terms of pain score (with a surface under the cumulative ranking curve [SUCRA] value of 80.0 and a mean rank of 2.2). Also, the minimally invasive quadriceps-sparing (MQS) approach led to better outcomes in terms of ROM (with a SUCRA value of 90.0 and a mean rank of 1.6). However, the subvastus (SV) and quadriceps-splitting (Qsplitt) approaches led to better outcomes in terms of reduction in adverse effects (SV: SUCRA value of 80.0 and a mean rank of 2.4; Qsplitt: SUCRA value of 70.0 and a mean rank of 3.1). According to this NMA, minimally invasive approaches of TKA led to better outcomes in terms of pain score and ROM, while conventional approaches of TKA led to better outcomes in terms of safety. Therefore, orthopedic surgeons should consider various factors when choosing the TKA approach. PROSPERO: CRD42024548966

Building Bridges, Not Dependencies: Empowering Local Surgeons as the Future of Global Arthroplasty Outreach.

To evaluate the feasibility, radiological accuracy, and early clinical outcomes of robotic-assisted conversion of partial knee arthroplasty (PKA) to total knee arthroplasty (TKA) using the ROSA system. Feasibility was defined as successful robotic registration and completion of the procedure using standard primary components without femoral components or augments. A retrospective cohort of 23 consecutive conversions (medial or lateral unicompartmental and patellofemoral arthroplasties) was analyzed. The minimum follow-up was 12 months. Clinical outcomes were assessed with the Oxford Knee Score (OKS), visual analogue scale (VAS) for pain, and patient satisfaction. Radiological accuracy was evaluated by comparing planned with achieved component alignment (medial proximal tibial angle (MPTA), lateral distal femoral angle (LDFA), and hip-knee-ankle (HKA)) using paired t-tests, two one-sided tests for equivalence (SD 1.5°), and Bland-Altman analysis. All cases were successfully registered with the robot and completed without femoral components or augments; 22 of 23 used standard primary components. The mean OKS improved from 17.2 (SD 5.5) to 40.0 (SD 5.0) and VAS pain decreased from 6.7 (SD 1.5) to 1.6 (SD 1.6) (p < 0.001). The mean absolute error between planned and achieved alignment was 0.8° for MPTA and 0.3° for LDFA, confirming accurate restoration, while HKA showed greater variability (mean bias 1.37°; limits -4.1° to 6.9°). One secondary patellar resurfacing was required; no other complications occurred. Robotic-assisted conversion of PKA to TKA was feasible, bone-preserving, and resulted in significant clinical improvement at 12 months, with precise component alignment but slightly more variation in overall mechanical axis restoration.

Long-term outcomes and predictors of failure after medial opening-wedge high tibial osteotomy: a 138-knee cohort with up to 10-year follow-up.

Background: Tibial shaft fractures distal to total knee arthroplasty (TKA) are commonly treated with plate fixation, which requires prolonged weight-bearing restriction. Although intramedullary nailing (IMN) has been attempted in selected cases, its feasibility remains controversial. This study aimed to assess the radiographic feasibility of IMN using anatomical parameters on lateral knee radiographs. Methods: A total of 271 lateral knee radiographs after TKA (January 2022 to October 2023) were retrospectively reviewed. Nail corridor and superior and inferior tibial tuberosity angles were measured on true lateral views. Tibial component size, keel length, BMI, age, and sex were analyzed for their association with nail corridor dimensions. Calibration was performed using known implant sizes. Results: Of the 271 lateral knee radiographs reviewed, 248 patients were included in the final analysis. The mean nail corridor was 9.27 ± 2.41 mm. The average superior and inferior tibial tuberosity angles were 105.88° and 155.79°, respectively. The tibial component size and keel length were not correlated with the nail corridor. In contrast, both superior (β = 0.252, p < 0.001) and inferior (β = 0.148, p = 0.003) tibial tuberosity angles were significantly associated with the nail corridor. No differences were observed in sex or BMI. Conclusions: IMN may be radiographically feasible in selected patients with tibial shaft fractures distal to TKA. The superior and inferior tibial tuberosity angles are anatomical parameters associated with the nail corridor and may serve as reference measures during preoperative radiographic assessment.

Unicompartmental knee arthroplasties (UKAs) are often revised to total knee arthroplasty (TKA), but concerns remain surrounding revision rates and perioperative outcomes of UKA revision to TKA. The primary aim of this study was to compare revision rates of UKA revision to TKA to matched cohorts of both primary and revision TKA procedures. Secondary aims were to compare the intraoperative outcomes, implants characteristics, and functional outcomes. This was a single centre cohort study of all consecutive patients who underwent UKA revision to TKA from 2012 to 2023. Patients undergoing elective revision of UKA to TKA with minimum one year follow-up were included and matched 1:1:1 to patients undergoing primary TKA and first-time aseptic revision TKA. Demographic data, indications for surgery, surgical details, and postoperative outcomes, including revision rates, complications, WOMAC scores and range of motion (ROM), were collected and compared between groups. Differences in continuous data were assessed using unpaired Students t-test and categorical data using Pearson's Chi-squared test or Fisher's exact test where applicable. When comparing differences in continuous outcomes between the three procedure groups, one-way analysis of variance (ANOVA) with post hoc Tukey HSD test was utilized. Kaplan-Meier survival analysis with log-rank test was performed for complications requiring reoperation. Statistical significance for all analyses was set at α=0.05. Exactly 100 patients were identified that underwent a revision of a UKA to TKA during the study period, that were matched to primary and revision TKAs (total n=300). No significant difference was found in revision rates between UKA to TKA and revision TKA groups, though reoperation rates were higher for UKA revision compared to primary TKA (p=0.005) (Table 1). UKA revision to TKA cases had longer operative times (103.0min vs. 72.7min, p There was no difference in level of polyethylene bearing constraint between primary and revision UKA to TKA cases, however, revision TKA cases more commonly required constrained condylar knee level constraint. UKA revision to TKA demonstrated ROM similar to primary TKA and superior to revision TKA (p=0.05). The conversion of a UKA to a TKA is more complex than performing a primary TKA but less so than a revision TKA. Patients should be warned that these cases have higher revision and reoperation rates than primary TKAs, however, functional outcomes at 1-year and range of motion are similar to primary TKA. Typically, a standard posterior-stabilized implant can be utilized for this conversion, however, surgeons should be prepared that these cases often require stems and augments on the tibial side. For any figures or tables, please contact the authors directly.

BackgroundEnhanced Recovery After Surgery (ERAS) is a multidisciplinary, evidence-based protocol designed to accelerate patient recovery after surgery. While applied to total knee arthroplasty (TKA) to optimize perioperative care, a significant risk of early postoperative pain persists. This study aims to investigate the current status and identify key high-risk factors for early pain in TKA patients under ERAS, facilitating the development of targeted strategies to alleviate pain and enhance recovery.MethodsWe conducted a retrospective analysis of 183 patients who underwent TKA under the ERAS protocol at our hospital. On postoperative day 3, patients were categorized using the Numerical Rating Scale (NRS): those with NRS scores ≤3 formed the mild pain group (n=132), and those with scores >3 constituted the moderate-to-severe pain group (n=51). Clinical data were compared, and univariate along with multivariate logistic regression analyses were employed to identify independent risk factors for early postoperative pain.ResultsOf the 183 patients, 51 (27.87%) experienced moderate-to-severe pain. Comparative analysis revealed significant differences between the two groups in intraoperative tourniquet time, preoperative Hamilton Anxiety Scale (HAMA) score, preoperative quadriceps thickness, and preoperative Knee Society Score (KSS). Multivariate analysis confirmed these four factors as independent risk factors. A predictive nomogram model built on these factors demonstrated good calibration and a high predictive value, with an Area Under the Curve (AUC) of 0.892. Furthermore, NRS scores showed a positive correlation with tourniquet time and HAMA scores, and a negative correlation with quadriceps thickness and KSS scores.ConclusionA notable proportion of TKA patients under ERAS still experience moderate-to-severe early postoperative pain. This pain is independently associated with longer tourniquet time, higher preoperative anxiety, thinner quadriceps, and lower preoperative KSS. These factors are valuable for predicting pain, enabling early targeted interventions to minimize its occurrence and promote recovery.

IntroductionPatella fractures are articular injuries that can alter knee biomechanics, disrupt joint contact forces, and promote cartilage degeneration. However, progression to reconstructive surgery is not fully characterized. This study investigates the risk of progression to total knee arthroplasty (TKA) following patella fractures and assesses whether initial operative versus nonoperative management impacts this risk.MethodsWe retrospectively analyzed TKA progression in patients with patella fractures using synthetic data from a large Level I academic trauma center (1996–2024). Patients were identified by historic diagnostic codes for patella fractures and TKA. Age-stratified TKA rates were compared to published national data, and indirect standardization was used to calculate the age-adjusted standardized incidence ratio (SIR), risk difference (RD), and attributable risk percent (AR%).ResultsAmong 3212 native patella fractures, 263 patients (8.2%) later underwent TKA. The mean age at fracture was 58.1 years (SD 17.5) with a mean time to TKA of 4.1 years (SD 4.9). The SIR for TKA was 1.6 (95% CI 1.3–1.9), RD 3.1%, and AR% 37.2%. In the 406 operatively treated fractures (mean age 55.3 years, SD 18.6; 60.8% female), TKA occurred in 5.4% (SIR 1.4, 95% CI 0.9–2.2), compared to 8.6% in the 2,806 nonoperatively treated fractures (mean age 58.5 years, SD 17.4; 61.8% female; SIR 2.1, 95% CI 1.8–2.3) (p = 0.04).ConclusionIndividuals with patella fractures face an increased lifetime risk of advanced joint degeneration and subsequent TKA compared to the general population, with nonoperative treatment linked to a higher risk than operative management. Further analysis of initial injury patterns, radiographic findings, and patient factors are in need for further research to understand and validate these findings.

Three-year experience with training courses using a TKA simulator - clinical impact and lessons learned.

Medial Meniscus Posterior Root Tear Repairs Show Osteoarthritis Progression Over Time With Higher Rates Seen With Higher Body Mass Index.

The long-term outcomes of palliative high tibial osteotomy (PO) remain insufficiently defined. This study compared the clinical and radiological outcomes of PO with those of corrective osteotomy (CO) in patients with varus knee deformity. Secondary aim was to evaluate arthroplasty-free survival. It was hypothesized that PO and CO would yield comparable results and similar conversion rates to total knee arthroplasty (TKA). A retrospective cohort study was conducted on patients who underwent lateral closing wedge-high tibial osteotomy (LCW-HTO) between 2001 and 2017. Patients with extra-articular varus deformity (hip-knee-ankle angle [HKA] < 177°, lateral distal femoral angle [LDFA] > 90° or medial proximal tibial angle [MPTA] < 85°) were assigned to the CO group. Those with intra-articular deformity and normal MPTA and LDFA were assigned to the PO group. Radiographic evaluation included HKA, MPTA, LDFA, joint line obliquity (JLO) and joint line convergence angle (JLCA). Clinical outcomes were assessed using the Hospital for Special Surgery (HSS) score, International Knee Documentation Committee (IKDC) subjective score, Numeric Rating Scale (NRS) for pain, Tegner Activity Scale and Crosby-Insall grading. Forty patients were included, 20 in each group. The mean age was 49 ± 11 years, and the mean follow-up was 10.5 ± 2.9 years. Preoperative HKA averaged 174° ± 3.3° and improved to 179° ± 1.5°. Moreover, 25% of PO patients and 10% of CO patients postoperatively exceeded the JLO threshold of ≤4°. Both groups demonstrated significant clinical improvement, with no between-group differences except for higher HSS scores in the PO group. Osteoarthritis (OA) progression was limited, and TKA conversions were infrequent. PO may represent an effective joint-preserving option for intra-articular varus deformity. Despite less optimal correction of JLO and JLCA, PO achieved clinical and radiological outcomes comparable to CO, with similarly low conversion rates to TKA. Level IV, retrospective cohort study.

Patellofemoral arthroplasty (PFA) is a joint-sparing alternative to total knee arthroplasty (TKA) for isolated patellofemoral osteoarthritis, offering symptom relief while preserving tibiofemoral compartments and bone stock compared with TKA, particularly in younger and active patients. However, persistent anterior knee pain and patellar instability remain the leading causes of early failure, even when prosthetic components are stable and tibiofemoral degeneration is absent. This study aimed to describe a combined, nonprosthetic surgical strategy for symptomatic PFA failure due to patellar instability and to propose an algorithm-based framework for clinical decision-making. A 54-year-old woman presented with chronic anterior knee pain and recurrent instability four years after isolated PFA. Imaging confirmed stable and well-aligned prosthetic components with preserved tibiofemoral compartments but consistent lateral patellar subluxation. The patient was treated using a joint-preserving approach combining medial patellofemoral ligament (MPFL) reconstruction with hamstring autograft, anteromedial tibial tubercle osteotomy (TTO), and vastus medialis obliquus (VMO) advancement. Clinical outcomes were assessed with the Kujala and International Knee Documentation Committee (IKDC) scores at six weeks and three months. At three months, the Kujala score improved from 54 to 78, and the IKDC subjective score increased from 38 to 69. The patient reported significant pain reduction, restoration of patellar stability, and functional recovery. No recurrent instability, surgical complications, or implant-related problems were observed. Radiographs confirmed correct alignment and congruent prosthetic components. A combined approach addressing soft-tissue, bony, and dynamic stabilizers may provide an effective, joint-preserving alternative to TKA in selected patients with symptomatic PFA failure caused by instability. The algorithm presented may assist in surgical decision-making and optimize patient outcomes. V.

Proximal fibular osteotomy (PFO) is an emerging joint-preserving procedure for medial compartment knee osteoarthritis (OA), with most evidence derived from East Asian populations. Its safety and efficacy in Western patients remain underexplored. This prospective single-centre study, conducted at a tertiary university hospital in Greece (Southern Europe), evaluated 27 patients (30 knees) with medial compartment OA or knee OA with predominantly medial symptoms who underwent PFO. Primary outcomes were changes in VAS pain, Knee Society Score (KSS), Oxford Knee Score (OKS), KOOS-Jr, and EQ-5D-5L at 12 months. Secondary outcomes included postoperative complications and conversion to total knee arthroplasty (TKA). At 12 months, all outcomes improved significantly from baseline (p < 0.001), exceeding established minimal clinically important differences: VAS -4.4, KSS +27.9, OKS +14.8, KOOS-Jr +20.6, EQ-5D-5L + 0.27. One knee (3.3%) converted to TKA due to persistent pain. Peroneal nerve-related symptoms occurred in 36.7% of knees but resolved by 6 months. In this European (Greek) cohort, PFO provided substantial pain relief, functional improvement, and quality-of-life gains at 12 months with a favorable safety profile. These findings align with prior reports from East Asian populations and suggest that PFO may be a viable minimally invasive option for carefully selected Western patients with mild-to-moderate varus OA and medial compartment symptoms. Further high-quality research is needed to confirm these results and define PFO's role in knee OA management.

This study aimed to describe the causes of aseptic failure leading to conversion from unicompartmental knee arthroplasty (UKA) to total knee arthroplasty (TKA) and to report implant selection and mid-term outcomes in a high-volume orthopaedic centre. In this retrospective single-centre case series, 27 patients (13 women, 14 men; mean age 68.9 years, range 55-81) undergoing conversion from UKA to TKA between January 2013 and December 2020 were included. Causes of UKA failure, type of revision implant (posterior-stabilised [PS], constrained posterior-stabilised [CPS] or legacy constrained condylar knee [LCCK]), and use of tibial stem extensions were recorded. Implant survival after conversion was estimated using Kaplan-Meier analysis, and re-revision rates were documented. Absolute numbers with percentages were reported. The most common causes of UKA failure were periprosthetic tibial fracture (10/27; 37%), tibial component loosening (8/27; 30%) and progression of osteoarthritis (7/27; 26%). PS implants were used in 17 patients (63%; 6 with cemented tibial stem), CPS in 9 (33%; all with stems) and LCCK in 1 (4%; with stem). Overall, tibial stem extensions were used in 16 cases (59%). At a mean follow-up of 23 months (range 0-89), 2 patients (7%) underwent re-revision: one for tibial loosening and one for instability. Kaplan-Meier analysis estimated a median implant survival of 74 months (SD 17.1; 95% CI: 40.6-107.4 months). In this specialised high-volume centre, conversion of UKA to TKA was most performed for mechanical failure or disease progression. Most cases could be managed with PS implants, with selective use of stems or higher constraint when indicated. Re-revisions were rare, but findings should be interpreted cautiously given the small sample size, variable follow-up and potential selection bias. Level IV.

BACKGROUNDKnee osteoarthritis (OA) is a degenerative joint disease traditionally viewed through the lens of cartilage degradation. However, emerging evidence positions subchondral bone pathology - particularly bone marrow lesions (BMLs) - as a key contributor to pain, progression, and structural deterioration. Mesenchymal stem cell exhaustion within the osteoarthritic subchondral zone further impairs intrinsic repair mechanisms, reinforcing the rationale for biologic interventions.AIMTo evaluate the clinical efficacy of bone marrow aspirate concentrate (BMAC) therapy for knee OA, comparing subchondral vs intra-articular delivery routes, and elucidating the therapeutic impact on symptom relief and structural preservation.METHODSFollowing Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines, five clinical studies were included - comprising three randomized controlled trials and two prospective cohorts - with pooled data from 298 knees. Data on functional outcomes, imaging findings, and progression to total knee arthroplasty (TKA) were extracted and qualitatively synthesized.RESULTSSubchondral BMAC injections demonstrated superior improvements compared to intra-articular injection or placebo: Knee Injury and Osteoarthritis Outcome Score improved from 49.1 ± 1.9 to 61.2 ± 6.3 at 12 months (P < 0.05), Knee Society Score increased from 57 ± 12 to 87.3 ± 12 at two years, and Western Ontario and McMaster Universities Arthritis Index scores showed significant improvement favoring combined approaches. Magnetic resonance imaging analyses revealed mean BML volume regression of 2.1 cm3, with 80% of knees avoiding TKA over 13-year follow-up. Magnetic resonance imaging analyses revealed regression of BMLs and increased cartilage preservation in subchondral-treated knees. Long-term data indicated delayed progression to TKA and biomechanical improvements (e.g., Hip-Knee-Ankle angle correction). No major adverse events were reported.CONCLUSIONTargeting subchondral bone with BMAC addresses underlying OA pathology and may offer disease-modifying potential beyond symptom relief. These findings support a paradigm shift toward whole-joint biologic therapy, positioning the subchondral matrix as a therapeutic epicenter in OA management.