Does knee awareness differ between different knee arthroplasty prostheses? A matched, case-control, cross-sectional study.

BACKGROUND: Low knee awareness after Total Knee Arthroplasty (TKA) has become the ultimate goal in trying to achieve a natural feeling knee that meet patient expectations. To accommodate this manufacturers of TKAs have developed new prosthetic designs that potentially could give patients a more natural feeling knee during activities. The purpose af this study was to compare the Forgotten Joint Score (FJS) and Oxford Knee Score (OKS) of patients treated with a previous generation standard Cruciate Retaining (CR) TKA to the scores obtained by patients treated with a newer generation CR TKA or a mobile bearing CR TKA. METHODS: We identified all patients receiving a new generation CR TKA or mobile bearing TKA at our institution between 2010 and 2012. These were matched to a population of patients receiving a standard CR TKA regarding age, gender, year of surgery, Kellgren-Lawrence (KL) grade and pre- and postoperative knee alignment. Patients were asked to complete the FJS and OKS questionnaires. Of the 316 patients completing the survey 64 standard CR TKAs to 35 new generation CR TKAs and 121 standard CR TKAs to 68 mobile bearing TKAs were matched. The FJS and OKS scores of the three TKA designs were compared. RESULTS: When comparing the new generation CR TKAs to the standard CR TKAs we found statistically significant higher OKS and FJS scores (6 (p = 0.04) and 16 (p = 0.03) points respectively) for the new generation CR TKAs. When comparing the mobile bearing TKAs to the standard CR TKAs we found a statistically significant higher OKS score (3 points, p = 0.04), and a higher but non-significant FJS score (4 points, p = 0.48) for the mobile bearing TKAs. CONCLUSIONS: Patients receiving the new generation CR TKA obtained higher FJS and OKS scores when compared to patients receiving a standard CR TKA, indicating that the use of this newer prosthetic design facilitate less knee awareness and better function after TKA.

Good validity and reliability of the forgotten joint score in evaluating the outcome of total knee arthroplasty.

Background and purpose - When evaluating the outcome after total knee arthroplasty (TKA), increasing emphasis has been put on patient satisfaction and ability to perform activities of daily living. To address this, the forgotten joint score (FJS) for assessment of knee awareness has been developed. We investigated the validity and reliability of the FJS. Patients and methods - A Danish version of the FJS questionnaire was created according to internationally accepted standards. 360 participants who underwent primary TKA were invited to participate in the study. Of these, 315 were included in a validity study and 150 in a reliability study. Correlation between the Oxford knee score (OKS) and the FJS was examined and test-retest evaluation was performed. A ceiling effect was defined as participants reaching a score within 15% of the maximum achievable score. Results - The validity study revealed a strong correlation between the FJS and the OKS (intraclass correlation coefficient (ICC) = 0.81, 95% CI: 0.77-0.85; p < 0.001). The test-retest evaluation showed almost perfect reliability for the FJS total score (ICC = 0.91, 95% CI: 0.88-0.94) and substantial reliability or better for individual items of the FJS (ICC? 0.79). We found a high level of internal consistency (Cronbach's? = 0.96). The ceiling effect for the FJS was 16%, as compared to 37% for the OKS. Interpretation - The FJS showed good construct validity and test-retest reliability. It had a lower ceiling effect than the OKS. The FJS appears to be a promising tool for evaluation of small differences in knee performance in groups of patients with good clinical results after TKA.

What is the optimal alignment of the tibial and femoral components in knee arthroplasty?

BACKGROUND: Surgeon-dependent factors such as optimal implant alignment are thought to play a significant role in outcome following primary total knee arthroplasty (TKA). Exact definitions and references for optimal alignment are, however, still being debated. This overview of the literature describes different definitions of component alignment following primary TKA for (1) tibiofemoral alignment in the AP plane, (2) tibial and femoral component placement in the AP plane, (3) tibial and femoral component placement in the sagittal plane, and (4) rotational alignment of tibial and femoral components and their role in outcome and implant survival. METHODS: We performed a literature search for original and review articles on implant positioning following primary TKA. Definitions for coronal, sagittal, and rotational placement of femoral and tibial components were summarized and the influence of positioning on survival and functional outcome was considered. RESULTS: Many definitions exist when evaluating placement of femoral and tibial components. Implant alignment plays a role in both survival and functional outcome following primary TKA, as component malalignment can lead to increased failure rates, maltracking, and knee pain. INTERPRETATION: Based on currently available evidence, surgeons should aim for optimal alignment of tibial and femoral components when performing TKA.

Do patients care about higher flexion in total knee arthroplasty? A randomized, controlled, double-blinded trial.

BACKGROUND: Little information exists to support that patients care about flexion beyond what is needed to perform activities of daily living (ADL) after Total knee arthroplasty (TKA). The purpose of this study was to investigate if the achievement of a higher degree of knee flexion after TKA would result in a better patient perceived outcome. METHODS: The study is a randomized, double-blinded, controlled trial in which 36 patients (mean age: 67.2 yrs) undergoing one-stage bilateral TKA randomly received a standard cruciate-retaining (CR) TKA in one knee and a high-flex posterior-stabilized (PS) TKA in the contra lateral knee. At follow-up ROM, satisfaction, pain, "feel" of the knee and the abilities in daily activities were assessed. RESULTS: At 1-year follow-up we found an expected significantly higher degree of knee flexion of 7° in the high-flex knees (p = 0.001). The high-flex TKA's showed a mean active flexion of 121°. In both TKA's the median VAS pain score was 0, the median VAS satisfaction score was 9, and the median VAS score of the patient "feel" of the knee was 9 at 1-year follow-up. Further, there were no significant differences between the knees in the performance of daily activities. CONCLUSIONS: As expected the high-flex TKA showed increased knee flexion, but no significant differences in the patient perceived outcomes were found. This suggests little relevance to the patients of the difference in knee flexion - when flexion is of this magnitude - as pain free ROM and high patient satisfaction were achieved with both TKA's. TRIAL REGISTRATION: ClinicalTrials.gov: NCT00294528.

The risk of manipulation under anesthesia due to unsatisfactory knee flexion after fast-track total knee arthroplasty.

BACKGROUND: Fast-track TKA has significantly shortened the time available for physiotherapists to optimize knee ROM before discharge. Safety aspects concerning knee stiffness and the need for manipulation in a fast-track setting need to be illuminated. The study aims were to analyze if fast-track TKA can be considered safe considering rates of knee manipulation and if there is an association between knee ROM at time of discharge and the need for later manipulation. METHODS: Primary TKAs operated in 2011 at our institution were eligible for inclusion. The study group consisted of 359 TKAs. RESULTS: Manipulation of the knee was performed in 21 of 359 TKAs (5.8%). Seventy-one percent were discharged with a flexion ≥70° combined with an extension deficit of ≤10°. The occurrence of MUA for these patients was 4.3%. The prevalence of knee manipulation showed a statistically significant association with the achieved knee flexion at discharge (p=0.02). Median length of stay was two days. CONCLUSION: Compared with literature findings fast-track TKA surgery may be considered safe based on the acceptable rate of knee manipulations after TKA (5.8%). We suggest ROM of ≥70° flexion combined with an extension deficit of ≤10° as an "optimal-zone" for ROM at discharge. The reason for this is the low occurrence of MUA (4.3%) in relation to the large amount of TKAs it represents (71%). The indication for MUA is multifactorial and ROM at discharge serves only as an indicator of later MUA risk.

Indications for knee arthroplasty have remained consistent over time.

INTRODUCTION: Between 2004 and 2009, the incidence of primary total knee arthroplasty (TKA) in Denmark has almost doubled. It has been speculated that this increase may be a result of patients being operated on weaker indications. The purpose of this study was to compare preoperative degrees of osteoarthritis and health-related quality of life (QoL) in patients receiving primary TKA in 2004 and 2009. MATERIAL AND METHODS: We identified 154 and 369 primary TKAs inserted at our institution in 2004 and 2009, respectively. Patients had been invited to complete the Short Form (SF)-36 questionnaire preoperatively. Two groups of patients that were representative with regard to age and gender were randomly sampled and compared (n = 44 in 2004 versus n = 106 in 2009). The Kellgren-Lawrence (K-L) grade of osteoarthritis was assessed on preoperative radiographs in all patients. RESULTS: We found no statistically significant differences in gender distribution or mean age at surgery. We reached K-L grades of 3-4 in 52.4% and 49.6% in 2004 and 2009, respectively (p = 0.57). The preoperative mean SF-36 physical component scores were 32.6 and 33.7, respectively (p = 0.44). The preoperative mean SF-36 mental component scores were 43.0 in 2004 and 49.3 (i.e. 6.3 points higher) in 2009 (p = 0.003). CONCLUSION: Preoperative degrees of osteoarthritis and physical health-related QoL did not change from 2004 to 2009. Thus, it seems that these components of operative indications have not weakened. The increased preoperative SF-36 mental component score of these patients may have had a positive effect on postoperative outcomes. FUNDING: not relevant. TRIAL REGISTRATION: not relevant. TRIAL REGISTRATION: not relevant.