Anterior knee pain (AKP) is the commonest complication of total knee arthroplasty (TKA). This study aims to assess whether sagittal femoral component position is an independent predictor of AKP after cruciate retaining single radius TKA without primary patellofemoral resurfacing. From a prospective cohort of 297 consecutive TKAs, 73 (25%) patients reported AKP and 89 (30%) reported no pain at 10 years. Patients were assessed pre-operatively and at 1, 5 and 10 years using the short form 12 and Oxford Knee Score (OKS). Variables assessed included demographic data, indication, reoperation, patella resurfacing, and radiographic criteria. Patients with AKP (mean age 67.0 (38–82), 48 (66%) female) had mean Visual Analogue Scale (VAS) Pain scores of 34.3 (range 5–100). VAS scores were 0 in patients with no pain (mean age 66.5 (41–82), 60 (67%) female). Femoral component flexion (FCF), anterior femoral offset ratio, and medial proximal tibial angle all differed significantly between patients with AKP and no pain (p<0.001), p=0.007, p=0.009, respectively). All PROMs were worse in the AKP group at 10 years (p<0.05). OKSs were worse from 1 year (p<0.05). Multivariate analysis confirmed FCF and Insall ratio <0.8 as independent predictors of AKP (R. 2. = 0.263). Extension of ≥0.5° predicted AKP with 87% sensitivity. AKP affects 25% of patients following single radius cruciate retaining TKA, resulting in inferior patient-reported outcome measures at 10 years. Sagittal plane positioning and alignment of the femoral component are important determinants of long-term AKP with femoral component extension being a major risk factor

Background. Navigation in total knee replacement is controversially discussed in the literature. In our previous study, femoral component positioning was more accurate with computed navigation than with conventional implantation techniques, however tibial positioning showed similar results. Moreover there were no differences between image-free and image-based navigation techniques. To what extent more accurate femoral positioning has an impact on the clinical mid-term follow up is not known. Methods. At a mean follow-up interval of 5.3 years, seventy-one patients (84.5%) returned for a review and were examined clinically and radiographically, with use of a methodology identical to that used preop and at 2 years, using the subjective value, the Knee Society Score (KSS), and a.p. and true lateral standard radiographs respectively. Complications, re-operations, persisting pain and resulting range of motion were registered. Results. Four patients in the image-based (2x late-onset infection, 1x femoral impingement, 1x component malalignment), 2 in the conventional group (2x component malalignment) and 1 patient in the image-free navigated group (arthoscopic debridement for arthrofibrosis) needed reoperation in the mean time. 59 of the 71 patients were very satisfied and satisfied at 5.3 years folllow up: (conventional: 19 of 25 (77±8 years); image-based navigation: 18 of 22 (77±10 years); image-free navigation: 22 of 24 (78±7 years)). The mean average of the Knee Society Score was 92.3(range 47 to 98). Compared to the conventional (KSS: 93.9±8,0) and image-free (KSS: 94.0±6,43) group, the KSS in the image-based group was insignificantly lower (KSS: 90±13,6) (p< 0,05). Radiographically, two patients in the conventional group showed a lysis on the lateral and medial tibia plateau of <1 mm without any clinical significance. There was no need for reintervention. There were no significant differences concerning remainig pain (conventional: 24%; image-based 18%; image-free: 8,5%), ROM and ligamental stability. Conclusion. Radiographical and clinical mid-term results after TKA yielded good and excellent results independent of the computed navigation and its type. Even a more accurate femoral component positioning in the patients cohort has been shown, we couldn't find a significant difference concerning the clinical outcome 5.3 years after conventional, image-based and image-free total knee arthroplasty. Despite of increased costs and time for navigated techniques we cannot show a mid-term benefit in functional and subjectiv outcome compared to conventional techniques