Within-day test-retest reliability of an accelerometer-based method for registration of step time symmetry during stair descent after ACL reconstruction and in healthy subjects.

Background: Symmetry during stair descent can potentially be used as an early functional measure after anterior cruciate ligament reconstruction (ACLR). We have developed a novel application of a single accelerometer-based inertial motion unit (IMU) to identify foot strikes and calculate step times in an ordinary stairway.Purpose: To examine within-day test-retest reliability and measurement error of step time and step time symmetry measured with a body-fixed IMU during stair descent in subjects early after ACLR and in healthy subjects.Methods: Subjects after ACLR were tested twice 6 weeks (N = 15) and twice 3 months (N = 26) postoperatively. Eighteen healthy subjects were tested twice on one occasion. Subjects descended a flight of stairs at preferred speed. Trunk accelerometry data were collected with an inertial motion unit (IMU). Mean step times (MSTs) and limb symmetry index (LSI) of MSTs were calculated. Clinical trials registration number: NCT01279759.Results: Intraclass Correlation Coefficient (ICC (1,1)) for within test-retest reliability varied from 0.87 to 0.96 for MSTs and from 0.58 to 0.87 for LSIs. The 95% confidence interval (CI) for a true value varied from ± 0.02 seconds (s) to ± 0.05 s for MSTs and from ± 4.6 percentage points (pp) to ± 6.6 pp for LSIs.Conclusion: Mean step times measured with a body-fixed IMU during stair descent and limb symmetry indexes calculated from these mean step times are precise and reliable during early post-operative rehabilitation after ACLR and in healthy subjects.

Association Between Psychological Readiness and Knee Laxity and Their Predictive Value for Return to Sport in Patients With Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Deciding when patients are ready to return to sport (RTS) after an anterior cruciate ligament (ACL) reconstruction (ACLR) is challenging. The understanding of which factors affect readiness and how they may be related is limited. Therefore, despite widespread use of RTS testing, there is a lack of knowledge about which tests are informative on the ability to resume sports. PURPOSE: To examine whether there is an association between knee laxity and psychological readiness to RTS after ACLR and to evaluate the predictive value of these measures on sports resumption. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: Patients aged ≥16 years engaged in physical activity/sports before injury were recruited at routine clinical assessment 9-12 months after ACLR. Exclusion criteria were concomitant ligament surgery at ACLR and/or previous ACL injury in the contralateral knee. At baseline, a project-specific activity questionnaire and the ACL-Return to Sport After Injury (ACL-RSI) scale were completed. Knee laxity was assessed by use of the Lachman test, KT-1000 arthrometer, and pivot-shift test. Two years after surgery, knee reinjuries and RTS status (the project-specific questionnaire) were registered. Associations between psychological readiness and knee laxity were evaluated with the Spearman rho test, and predictive ability of the ACL-RSI and knee laxity tests were examined using regression analyses. RESULTS: Of 171 patients screened for eligibility, 132 were included in the study. There were small but significant associations between the ACL-RSI score and the Lachman test (rho = -0.18; P = .046) and KT-1000 arthrometer measurement (rho = -0.18; P = .040) but no association between the ACL-RSI and the pivot-shift test at the time of recruitment. Of the total patients, 36% returned to preinjury sport level by 2 years after surgery. Higher age, better psychological readiness, and less anterior tibial displacement (KT-1000 arthrometer measurement) were significant predictors of 2-year RTS (explained variance, 33%). CONCLUSION: Small but significant associations were found between measurements of psychological readiness and anterior tibial displacement, indicating that patients with less knee laxity after ACLR feel more ready to RTS. ACL-RSI and KT-1000 arthrometer measurements were independent predictors of 2-year RTS and should be considered in RTS assessments after ACLR.

The Role of Psychological Readiness in Return to Sport Assessment After Anterior Cruciate Ligament Reconstruction.

BACKGROUND: Knowledge about the predictive value of return to sport (RTS) test batteries applied after anterior cruciate ligament reconstruction (ACLR) is limited. Adding assessment of psychological readiness has been recommended, but knowledge of how this affects the predictive ability of test batteries is lacking. PURPOSE: To examine the predictive ability of a RTS test battery on return to preinjury level of sport and reinjury when evaluation of psychological readiness was incorporated. STUDY DESIGN: Cohort study; Level of evidence, 2. METHODS: A total of 129 patients were recruited 9 months after ACLR. Inclusion criteria were age ≥16 years and engagement in sports before injury. Patients with concomitant ligamentous surgery or ACL revision surgery were excluded. Baseline testing included single-leg hop tests, isokinetic strength tests, the International Knee Documentation Committee (IKDC) Subjective Knee Form 2000, a custom-made RTS questionnaire, and the Anterior Cruciate Ligament-Return to Sport after Injury (ACL-RSI) scale. The RTS criteria were IKDC 2000 score ≥85% and ≥85% leg symmetry index on hop and strength test. At a 2-year follow-up evaluation, further knee surgery and reinjuries were registered and the RTS questionnaire was completed again. Regression analyses and receiver operating characteristic analyses were performed to study the predictive ability of the test battery. RESULTS: Out of the 103 patients who completed the 2-year follow-up, 42% returned to their preinjury level of sport. ACL-RSI 9 months after surgery (odds ratio [OR], 1.03) and age (OR, 1.05) predicted RTS. An ACL-RSI score <47 indicated that a patient was at risk of not returning to sport (area under the curve 0.69; 95% CI, 0.58-0.79), with 85% sensitivity and 45% specificity. The functional tests did not predict RTS. Six patients sustained ACL reinjuries and 7 underwent surgery for other knee complaints/injuries after RTS testing. None of the 29 patients who passed all RTS criteria, and were therefore cleared for RTS, sustained a second knee injury. CONCLUSION: ACL-RSI and age were predictors of 2-year RTS, while functional tests were not informative. Another main finding was that none of the patients who passed the 85% RTS criteria sustained another knee injury.

Anterior cruciate ligament-return to sport after injury scale: validation of the Norwegian language version.

PURPOSE: Evidence is emerging on the importance of psychological readiness to return to sport after anterior cruciate ligament (ACL) reconstruction. The ACL-Return to Sport after Injury scale (ACL-RSI) is developed to assess this. The aim of the current study was to translate ACL-RSI into Norwegian and examine the measurement properties of the Norwegian version (ACL-RSI-No). METHODS: ACL-RSI was translated according to international guidelines. A cohort of 197 ACL-reconstructed patients completed ACL-RSI-No and related questionnaires nine months post-surgery. One hundred and forty-six patients completed hop tests and 142 patients completed strength tests. Face and structural validity (confirmative factor analysis and explorative analyses), internal consistency [Cronbach's alpha (α)], test-retest reliability [Intraclass Correlation Coefficients (ICC)], measurement error [Standard error of measurement (SEM) and smallest detectable change at individual (SDCind) and group level (SDCgroup)] and construct validity (hypotheses testing; independent t tests, Pearson's r) were examined. RESULTS: ACL-RSI-No had good face validity. Factor analyses suggested that the use of a sum score is reasonable. Internal consistency and test-retest reliability were good (α 0.95, ICC 0.94 (95% CI 0.84-0.97) and measurement error low (SEM 5.7). SDCind was 15.8 points and SDCgroup was 2.0. Six of seven hypotheses were confirmed. CONCLUSIONS: ACL-RSI-No displayed good measurement properties. Factor analyses suggested one underlying explanatory factor for "psychological readiness"-supporting the use of a single sum score. ACL-RSI-No can be used in the evaluation of psychological readiness to return to sport after ACL injury. LEVEL OF EVIDENCE: III.

Criteria of gait asymmetry in patients with hip osteoarthritis.

Gait symmetry is often a goal for physiotherapy in patients with hip osteoarthritis and after total hip replacement. However, there is no agreement on criteria for pathological gait asymmetry. In this study we investigated discriminative abilities of trunk and footfall gait symmetry measures, and thereafter assessed whether a 10% cutoff value is valid as a general criterion of pathological gait asymmetry across measures. Anteroposterior, vertical, and mediolateral trunk symmetry, single support, and step length symmetry were obtained simultaneously by trunk accelerometry and an electronic walkway in 37 patients with end-stage hip osteoarthritis and 56 controls. Subjects walked six times along a 7-meter walkway at slow, preferred, and fast speed, before data were normalized for gait velocity. Anteroposterior, vertical, and single support symmetry measures showed best discriminating abilities. The general 10% criterion of gait asymmetry and optimal cutoff criteria calculated for each symmetry measure showed approximately equal total classification ability. However, the optimal cutoff criteria classified a high number of controls as having pathological gait asymmetry. The general criterion of 10% is valid with high total classification ability, does not classify asymmetry in able-bodied subjects as pathological, and is feasible for use on individual patients in the clinic as well as in research.

Changes in gait symmetry, gait velocity and self-reported function following total hip replacement.

OBJECTIVE: To investigate the magnitude of change at different time points in measures of gait symmetry, gait velocity and self-reported function following total hip replacement. DESIGN: Longitudinal with test occasions pre-surgery and 3, 6 and 12 months post-surgery. SUBJECTS: Thirty-four patients with hip osteoarthritis (mean age 63 years, standard deviation 11 years). METHODS: Subjects walked back and forth along a 7-m walkway at slow, preferred and fast speed. Anteroposterior, vertical and mediolateral trunk symmetry was assessed by accelerometry, while single support symmetry, step-length symmetry and gait velocity was simultaneously assessed by an electronic walkway. Self-reported function was assessed by Hip disability and Osteoarthritis Outcome Score. Gait symmetry data were normalized for gait velocity. Changes between test occasions were reported as effect size. RESULTS: All measures showed effect sizes > 0.30 from pre-operative to 12-months postoperative assessments, and improvements were significant (p < 0.05) in all measures, except mediolateral symmetry. In general, gait symmetry and gait velocity improved most 6 and 12 months postoperatively, while self-reported function improved most 3 months postoperatively. CONCLUSION: Early improvements were seen in self-reported function, suggesting immediate relief from stiffness and pain, while gait symmetry and velocity improved later postoperatively, suggesting that gait quality and performance require prolonged rehabilitation with postoperative guidance, muscular strengthening and motor relearning.