RESUMEN

INTRODUCTION: 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. METHODS: 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. RESULTS: 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). CONCLUSION: 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. LEVEL OF EVIDENCE: III.

Asunto(s)

Artroplastia de Reemplazo de Rodilla , Artropatías , Prótesis de la Rodilla , Humanos , Artroplastia de Reemplazo de Rodilla/efectos adversos , Rótula/cirugía , Incidencia , Estudios Retrospectivos , Articulación de la Rodilla/cirugía , Artropatías/cirugía , Rango del Movimiento Articular , Prótesis de la Rodilla/efectos adversos

RESUMEN

BACKGROUND: Extended oral antibiotic prophylaxis (EOA) has been shown to potentially reduce infection rates after high-risk primary total knee arthroplasties (TKAs) and reimplantations. However, data is limited regarding EOA after aseptic revision TKAs. This study evaluated the impact of EOA on infection-related outcomes after aseptic revision TKAs. METHODS: 904 aseptic revision TKAs from 2014-2019 were retrospectively identified. Patients who received EOA >24 hours perioperatively (n = 267) were compared to those who did not (n = 637) using an inverse probability of treatment weighting model. Mean age was 66 years, mean BMI was 33 kg/m2, and 54% were female. Outcomes included cumulative probabilities of any infection, periprosthetic joint infection (PJI), superficial infection, and re-revision or reoperation for infection. RESULTS: The cumulative probability of any infection after aseptic revision TKA was 1.9% at 90 days, 3.5% at 1 year, and 8.1% at 5 years. Patients without EOA had a higher risk of any infection at 90 days (HR = 7.1; P = .01), but not other time points. The cumulative probability of PJI after aseptic revision TKA was 0.8% at 90 days, 2.3% at 1 year, and 6.5% at 5 years. Patients without EOA did not have an increased risk of PJI. There were no differences in re-revision or reoperation for infection at any time point between groups. CONCLUSION: Extended oral antibiotics after aseptic revision TKA were associated with a 7-fold decreased risk of any infection at 90 days. The results suggest a potential role for EOA after aseptic revision TKA and warrant additional prospective studies. LEVEL OF EVIDENCE: Level III.

Asunto(s)

Artritis Infecciosa , Artroplastia de Reemplazo de Rodilla , Infecciones Relacionadas con Prótesis , Anciano , Profilaxis Antibiótica , Artritis Infecciosa/etiología , Artroplastia de Reemplazo de Rodilla/efectos adversos , Artroplastia de Reemplazo de Rodilla/métodos , Femenino , Humanos , Masculino , Estudios Prospectivos , Falla de Prótesis , Infecciones Relacionadas con Prótesis/etiología , Infecciones Relacionadas con Prótesis/prevención & control , Infecciones Relacionadas con Prótesis/cirugía , Reoperación/efectos adversos , Estudios Retrospectivos

RESUMEN

AIMS: Current guidelines consider analyses of joint aspirates, including leucocyte cell count (LC) and polymorphonuclear percentage (PMN%) as a diagnostic mainstay of periprosthetic joint infection (PJI). It is unclear if these parameters are subject to a certain degree of variability over time. Therefore, the aim of this study was to evaluate the variation of LC and PMN% in patients with aseptic revision total knee arthroplasty (TKA). METHODS: We conducted a prospective, double-centre study of 40 patients with 40 knee joints. Patients underwent joint aspiration at two different time points with a maximum period of 120 days in between these interventions and without any events such as other joint aspirations or surgeries. The main indications for TKA revision surgery were aseptic implant loosening (n = 24) and joint instability (n = 11). RESULTS: Overall, 80 synovial fluid samples of 40 patients were analyzed. The average time period between the joint aspirations was 50 days (SD 32). There was a significantly higher percentage change in LC when compared to PMN% (44.1% (SD 28.6%) vs 27.3% (SD 23.7%); p = 0.003). When applying standard definition criteria, LC counts were found to skip back and forth between the two time points with exceeding the thresholds in up to 20% of cases, which was significantly more compared to PMN% for the European Bone and Joint Infection Society (EBJIS) criteria (p = 0.001), as well as for Musculoskeletal Infection Society (MSIS) (p = 0.029). CONCLUSION: LC and PMN% are subject to considerable variation. According to its higher interindividual variance, LC evaluation might contribute to false-positive or false-negative results in PJI assessment. Single LC testing prior to TKA revision surgery seems to be insufficient to exclude PJI. On the basis of the obtained results, PMN% analyses overrule LC measurements with regard to a conclusive diagnostic algorithm. Cite this article: Bone Jt Open 2021;2(8):566-572.