Postoperative fixed flexion deformity greater than 10° lead to poorer functional outcome 10 years after unicompartmental knee arthroplasty.

PURPOSE: The primary aim of this study was to evaluate the influence of postoperative fixed flexion deformity (FFD) on the clinical outcomes 10 years after unicompartmental knee arthroplasty (UKA). The secondary aim was to identify predictors for the occurrence of postoperative FFD. METHODS: Patients who underwent UKA between 2003 and 2007 were prospectively followed up for 10 years. A total of 172 patients were categorized into 3 groups based on the amount of postoperative FFD: (1) 0° or less (Min-FFD), (2) 1°-9° (Mid-FFD), and (3) 10° or more (Max-FFD). Functional outcome was quantified using Knee Society Function Score (KSFS), Knee Society Knee Score (KSKS) and Oxford Knee Score (OKS). RESULTS: At 10 years after UKA, the mean KSKS and OKS were 6 ± 5 (95% CI 6-18, p = 0.050) and 5 ± 2 (95% CI 0-9, p = 0.041) points lower in patients with Max-FFD than those with Min-FFD. Other clinical outcomes were not different between groups. Patients with a higher preoperative body mass index (OR 1.122 per unit increase, 95% CI 1.006-1.253, p = 0.040) or worse preoperative FFD (OR 1.108 per unit increase, 95% CI 1.022-1.201, p = 0.013) were at increased risk of having postoperative FFD of 10° or more at 10 years after UKA. CONCLUSIONS: The clinical relevance of this study was to demonstrate the long-term negative correlation between severe postoperative FFD and functional outcome and, therefore, the importance of achieving good knee alignment after UKA. The authors recommend that FFD should be fully corrected intra-operatively if possible while preserving knee balance and stable dynamic function through full range of motion. LEVEL OF EVIDENCE: Prognostic level II.

Identifying an Ideal Time Frame for Staged Bilateral Total Knee Arthroplasty to Maximize Functional Outcome.

Compared with staged bilateral total knee arthroplasty (TKA), simultaneous bilateral TKA carries a higher risk of cardiac complications, pulmonary complications, and mortality, especially in patients with preexisting cardiopulmonary disease or advanced age. However, the period of time between staged TKAs that would eliminate these increased risks has yet to be determined. The purpose of this study is to evaluate complication rates and functional outcome in patients who underwent staged bilateral TKA and to determine an optimal time frame for the second knee. The authors retrospectively reviewed 306 patients who underwent staged bilateral TKA between 2002 and 2013. Patients were grouped into 31 to 90, 91 to 180, 181 to 270, and 271 to 365 days interval, where complication and 90-day readmission rates for the second TKA were identified. Patients were also assessed preoperatively and 2 years postoperatively using the Oxford knee score (OKS) and Short-Form (SF)-36. There was no significant difference in complication and 90-day readmission rates between the various groups. The functional outcome of the knees scored 2 years postoperatively using OKS and SF-36 showed comparable results across all four groups. Thus, the authors could not identify an ideal time frame for performing the second TKA with the objective of maximizing functional outcome.

Preoperative haemoglobin cut-off values for the prediction of post-operative transfusion in total knee arthroplasty.

PURPOSE: The purpose of this study is to determine preoperative haemoglobin cut-off values that could accurately predict post-operative transfusion outcome in patients undergoing primary unilateral total knee arthroplasty (TKA). This will allow surgeons to provide selective preoperative type and screen to only patients at high risk of transfusion. METHODS: A total of 1457 patients diagnosed with osteoarthritis and underwent primary unilateral TKA between January 2012 and December 2014 were retrospectively reviewed. Logistic regression analyses were applied to identify factors that could predict transfusion outcome. RESULTS: A total of 37 patients (2.5 %) were transfused postoperatively. Univariate analysis revealed preoperative haemoglobin (p < 0.001), age (p < 0.001), preoperative haematocrit (p < 0.001), and preoperative creatinine (p < 0.001) to be significant predictors. In the multivariate analysis with patients dichotomised at 70 years of age, preoperative haemoglobin remained significant with adjusted odds ratio of 0.33. Receiver operating characteristic curve identified the preoperative haemoglobin cut-off values to be 12.4 g/dL (AUC = 0.86, sensitivity = 87.5 %, specificity = 77.2 %) and 12.1 g/dL (AUC = 0.85, sensitivity = 69.2 %, specificity = 87.1 %) for age above and below 70, respectively. CONCLUSIONS: The authors recommend preoperative haemoglobin cut-off values of 12.4 g/dL for age above 70 and 12.1 g/dL for age below 70 to be used to predict post-operative transfusion requirements in TKA. To maximise the utilisation of blood resources, the authors recommend that only patients with haemoglobin level below the cut-off should receive routine preoperative type and screen before TKA. LEVEL OF EVIDENCE: IV.