RESUMEN
Patient specific alignment might improve clinical outcomes in total knee arthroplasty (TKA). Different alignment concepts are described, each providing specific features with theoretical benefits or possible disadvantages. Inverse kinematic alignment (iKA) is a new patient specific alignment concept with excellent reported clinical outcome and patient satisfaction at short-term follow-up. iKA is a tibia-first, gap balancing technique restoring the native tibial joint line obliquity (JLO). In each patient, within boundaries, equal medial and lateral tibial resections are performed, compensating for cartilage and bone loss. We describe the surgical technique of iKA using a robotic assisted system (Mako, Stryker, Kalamazoo, USA). A case series of 100 consecutive iKA cases is assessed and the bony resections and resection angles are reported. Both in the coronal plane and axial plane, iKA might offer advantages over existing alignment strategies, possibly providing optimal clinical outcome and durable long-term survival, regardless of the alignment is varus, neutral or valgus.
Asunto(s)
Artroplastia de Reemplazo de Rodilla , Prótesis de la Rodilla , Osteoartritis de la Rodilla , Artroplastia de Reemplazo de Rodilla/métodos , Fenómenos Biomecánicos , Humanos , Articulación de la Rodilla/diagnóstico por imagen , Articulación de la Rodilla/cirugía , Osteoartritis de la Rodilla/cirugía , Tibia/cirugíaRESUMEN
PURPOSE: Various alignment philosophies for total knee arthroplasty (TKA) have been described, all striving to achieve excellent long-term implant survival and good functional outcomes. In recent years, in search of higher functionality and patient satisfaction, a shift towards more tailored and patient-specific alignment is seen. The purpose of this study was to describe a restricted 'inverse kinematic alignment' (iKA) technique, and to compare clinical outcomes of patients that underwent robotic-assisted TKA performed by restricted iKA vs. adjusted mechanical alignment (aMA). METHODS: The authors reviewed the records of a consecutive series of patients that received robotic-assisted TKA with restricted iKA (n = 40) and with aMA (n = 40). Oxford Knee Score (OKS) and satisfaction on a visual analogue scale (VAS) were collected at a follow-up of 12 months. Clinical outcomes were assessed according to patient acceptable symptom state (PASS) thresholds, and uni- and multivariable linear regression analyses were performed to determine associations of OKS and satisfaction with six variables (age, sex, body mass index (BMI), preoperative hip-knee-ankle (HKA) angle, preoperative OKS, alignment technique). RESULTS: The restricted iKA and aMA techniques yielded comparable outcome scores (p = 0.069), with OKS, respectively, 44.6 ± 3.5 and 42.2 ± 6.3. VAS Satisfaction was better (p = 0.012) with restricted iKA (9.2 ± 0.8) compared to aMA (8.5 ± 1.3). The number of patients that achieved OKS and satisfaction PASS thresholds was significantly higher (p = 0.049 and p = 0.003, respectively) using restricted iKA (98% and 80%) compared to aMA (85% and 48%). Knees with preoperative varus deformity, achieved significantly (p = 0.025) better OKS using restricted iKA (45.4 ± 2.0) compared to aMA (41.4 ± 6.8). Multivariable analyses confirmed better OKS (ß = 3.1; p = 0.007) and satisfaction (ß = 0.73; p = 0.005) with restricted iKA. CONCLUSIONS: The results of this study suggest that restricted iKA and aMA grant comparable clinical outcomes at 12-month follow-up, though a greater proportion of knees operated by restricted iKA achieved the PASS thresholds for OKS and satisfaction. Notably. in knees with preoperative varus deformity, restricted iKA yielded significantly better OKS and satisfaction than aMA. LEVEL OF EVIDENCE: Level III, comparative study.
Asunto(s)
Artroplastia de Reemplazo de Rodilla , Prótesis de la Rodilla , Osteoartritis de la Rodilla , Artroplastia de Reemplazo de Rodilla/métodos , Fenómenos Biomecánicos , Humanos , Articulación de la Rodilla/cirugía , Osteoartritis de la Rodilla/cirugía , Satisfacción Personal , Resultado del TratamientoRESUMEN
More durable total knee arthroplasties (TKAs) are needed, due to the rising life expectancy, the higher activity levels of patients and the growing concerns about aseptic loosening being caused by metal hypersensitivity. In response, different hypoallergenic metal coatings have been developed for TKAs. However, possible adverse effects of these different metals (cobalt-chromium-molybdenum, zirconium, titanium and tantalum) have been neglected. The aim was to summarize the local and systemic adverse effects (including metal hypersensitivity), survival ratios, patient-reported outcome measures (PROMs) and the plasma metal ion concentrations of the different TKA coatings. A literature search on PubMed and EMBASE was performed. In total, 15 studies were found eligible. Common adverse effects of TKA were infection, loosening, pain, instability and hyper- coagulation disorders. Serious adverse effects related to TKA implants were not reported. The survival ratios and patient-reported outcome measures seem to confirm these good results. In contrast with chromium and cobalt, no significant differences were reported in the nickel, molybdenum and titanium concentrations. No significant differences between the hypoallergenic and standard TKA implants were found in terms of adverse effects, survival ratios and PROMs. A causal relationship between the common adverse effects and the different metals is unlikely. Due to the heterogeneity of the TKA implants used, no firm conclusions could be made. Further research with longer follow-up studies are needed to find possible adverse effects and differences. Thus far, the hypoallergenic implants seem to perform equal to the standard implants.