Agreement between inertial measurement unit and optoelectronic system to measure postural sway.

BACKGROUND: Optoelectronic systems and force platforms represent the gold standard for postural sway assessment, but pose disadvantages in terms of equipment, cost and preparation time. OBJECTIVE: Wearable inertial measurement units (IMUs) have been proposed to overcome these issues, but have never been compared to an optoelectronic system. The study aim was therefore to investigate agreement between inertial measurement unit and optoelectronic system in postural sway assessment. METHODS: Thirty healthy volunteers performed four balance tasks. IMU was placed on the sacrum (S2) with a retroreflective marker over the sensor and subjects' performance was simultaneously recorded by both systems. Total (TOT), anterior-posterior (AP) and medial-lateral (ML) length of trace, range, speed, root mean squared (RMS), and confidence ellipse were computed. RESULTS: ICCs revealed excellent correlations for Length-TOT, Length-AP and Speed-AP, good correlation for Length-ML, Speed-ML, Confidence Ellipse, Range-AP and RMS-AP, and moderate correlation for range-ML and RMS-ML. Bland-Altman plot showed greater estimation for Length-TOT, Length-AP, Speed-AP, confidence ellipse and RMS-AP using optoelectronic system, and for Length-ML, Range-AP, Range-ML, Speed-ML, RMS-ML using IMU. Both systems revealed the same differences among tasks. CONCLUSION: The excellent to good agreement of IMU for length of trace and speed parameters and its user-friendly application suggest its potential implementations in clinical practice.

Functional and postural recovery after bilateral or unilateral total hip arthroplasty.

One-stage bilateral total hip arthroplasty (THA) implies similar complication rate and hospitalization time to unilateral THA, but no studies have evaluated the functional and postural recovery in these patients. The aim of this study was to assess short-term functional and postural recovery in patients after one-stage bilateral or unilateral THA. Forty patients undergoing bilateral (n = 20) or unilateral (n = 20) THA were assessed by Timed Up and Go (TUG), Numeric Rating Scale (NRS), Tampa Scale of Kinesiophobia (TSK) and Body Weight Distribution Symmetry Index (BWDSI) during stand-to-sit (STS). Centre of Pressure (CoP) parameters and BWDSI during standing with eyes open (EO) and closed (EC) were also assessed. Data were collected one day before surgery, at three and seven days. No between-group differences were found for TUG, NRS and TSK at any time-point, showing similar mobility, pain and fear of movement in both groups. BWDSI during STS (P = 0.001) and standing (OE P = 0.007; CE P = 0.012) revealed differences over time in favor of patients with bilateral THA, who showed better symmetry in weight distribution. Shorter CoP path length was observed during standing in patients with unilateral THA (OE P = 0.023; CE P = 0.018), who mainly used their non-affected limb to maintain balance.

Gait analysis in patients after bilateral versus unilateral total hip arthroplasty.

BACKGROUND: Gait abnormalities were reported in patients after total hip arthroplasty (THA). One-stage bilateral THA was introduced for bilateral hip pathologies, showing similar clinical and surgical outcome to unilateral procedure. However, no studies analyze the gait features after bilateral THA surgery compared to unilateral THA. RESEARCH QUESTION: Are there differences in gait characteristics between bilateral and unilateral THA patients and are there differences between these cases and asymptomatic age-matched healthy subjects? METHODS: In this prospective observational study, thirty-five patients with bilateral (n = 18) or unilateral THA (n = 17) and twenty asymptomatic age-matched volunteers were studied. Participants underwent three-dimensional gait analysisin order to detect gait spatial-temporal and kinematic (Gait Variable Score - GVS) parameters. Mobility (Timed Up and Go - TUG), fear of movement (Tampa Scale of Kinesiophobia - TSK) and pain during walking (Numeric Rating Scale - NRS) were also assessed. Patients were evaluated the day before surgery and at seven days, whereas healthy subjects underwent a single evaluation. ANOVA was used to assess differences between the three groups at each time-point and within-group differences in bilateral and unilateral groups. RESULTS: At baseline, no differences between the two groups of patients were found. As expected, their gait spatial-temporal and kinematic parameters and functional variables were impaired with respect to healthy subjects, both before and after surgery. After surgery, GVS Pelvic-TILT closer to normative values, longer stance and shorter swing phases were found in bilateral cases compared to unilateral patients. Moreover, a higher NRS score was found in bilateral patients, whereas TUG and TSK revealed no differences between the two groups of patients. SIGNIFICANCE: The current findings, focusing on short-term effectiveness of bilateral THA, could assist physiotherapists in selecting the best ambulation training and an appropriate rehabilitation approach immediately after surgery.