The intra-rater reliability values achieved were suitable. Intraclass correlation coefficient values for inter-rater reliability remained below an acceptable level. Possible reasons and overcoming strategies were presented. The 95% limits of agreement were good, at less than ±2°.

Abstract:The study aimed to investigate whether pelvic tilt (PT) angles differ between the supine and upright position in symptom-free young adults. Additionally, the concurrent validity of the measurement system was tested on a pelvis phantom against a digital inclinometer. A new smartphone-based navigated ultrasound system was used to perform the measurements. The sample consisted of 12 symptom-free young adults. A multivariate regression model was used to analyze the data. The subjects' pelvis in supine position was significantly more tilted anteriorly (mean PT = −7.3 • , 95% C.I.: −10.6 to −3.9) than in upright position (mean PT = 0.8 • , 95% C.I.: −2.5 to 4.1) (mean. diff. 8.1 • ; p < 0.001). Rater and trial order had no significant effects on the measured PT angles (p = 0.5). The accuracy of the system when measuring PT angles on the pelvis phantom was 0.3 • (0.1 • to 0.7 • ) and 0.2 • (−0.09 • to 0.6 • ) for the supine and upright positions respectively. Pelvic tilt angles differed significantly between the supine and the upright position in symptom-free young adults. Concurrent validity showed no differences for measurements in the upright position and small (under 0.4 • ) significant differences for measurements in the supine position.

BackgroundThe purpose was to investigate whether patient-specific factors (PSF) and surgically modifiable factors (SMF), measured by means of a computer-assisted navigation system, can predict the Knee Society Scores (KSS) after total knee arthroplasty (TKA).MethodsData from 99 patients collected during a randomized clinical trial were used for this secondary data analysis. The KSS scores of the patients were measured preoperatively and at 4-years follow-up. Multiple regression analyses were performed to investigate which combination of variables would be the best to predict the 4-years KSS scores.ResultsWhen considering SMF alone the combination of four of them significantly predicted the 4-years KSS-F score (p = 0.009), explaining 18 % of its variation. When considering only PSF the combination of age and body weight significantly predicted the 4-years KSS-F (p = 0.008), explaining 11 % of its variation. When considering both groups of predictors simultaneously the combination of three PSF and two SMF significantly predicted the 4-years KSS-F (p = 0.007), explaining 20 % of its variation.ConclusionsYounger age, better preoperative KSS-F scores and lower BMI before surgery, a positive tibial component slope and small changes in femoral offset were predictors of better KSS-F scores at 4-years.

Level II, Prognostic study.

Some surgically modifiable factors are related to soft tissue balance. With computer-assisted surgery, it is possible to access these variables quantitatively. The aim of this analysis was to study the influence of gap balance on clinical outcomes within the first year after computer-navigated total knee arthroplasty (TKA). Based on navigation data, 3 independent variables reflecting gap balance were used to split the patients in 2 groups. The Knee Society Scores (Function [KSS-F] and Knee [KSS-K]) and the maximal knee flexion (MKF) measured preoperatively and at 3, 6 and 12 months were compared using analyses of variance (2×4 design) for repeated measures. Higher flexion-extension gap equality led to statistically higher KSS-F and KSS-K scores at 1 year (P=.02). Higher medial-lateral flexion gap equality led to superior mean MKF at all measurement points; however the differences were statistically only significant at 3 months (P=.01). The coefficients of variation of the variables used to select the patients were overall very low. With computer-assisted navigation, it is possible to access quantitatively the size of the medial and lateral flexion and extension gaps. Higher flexion-extension gap equality values led to statistically significant better KSS-F and KSS-K scores at 1 year. Higher medial-lateral flexion gap equality values led to better MKF values; however the differences were only statistically significant at 3 months. [Orthopedics. 2016; 39(3):S6-S12.].

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