Study of risk factors for knee and hip total replacement in an intrahospitalary cohort: a survival analysis

s / Osteoarthritis and Cartilage 22 (2014) S57–S489 S189 p 1⁄4 0.12–0.95). No or low correlations were found between the three measures of sensory function and the KOOS subscales (r 1⁄4 0.00–0.29, p 1⁄4 0.04–0.98) and the TAS (rs1⁄4 0.05–0.35, p1⁄4 0.02–0.75), respectively. Conclusions: The low, or lack of, correlation between TDPM and VPT suggest that these measures of sensory function cannot be used interchangeably in subjects with ACL injury or in their control counterparts. These measurements were weakly related to both hop performance, activity level and the patient’s perceived symptoms, function and activities implying that both knee kinesthesia and vibration sense only affect motor performance, activity level and patients’ perception of function to a limited degree. 323 STUDY OF RISK FACTORS FOR KNEE AND HIP TOTAL REPLACEMENT IN AN INTRAHOSPITALARY COHORT: A SURVIVAL ANALYSIS L. Rodriguez-Rodriguez, J.R. Lamas, P. Tornero, S. Baena, L. Abasolo, B. Fernandez-Gutierrez. Hosp. Clinico San Carlos, Madrid, Spain Purpose: Our aim was to analyze the influence of different demographic, clinical and radiographic variables in the rate of total knee and hip replacement. Methods: Consecutive patients diagnosed with knee and/or hip osteoarthritis (OA) attending the Rheumatology and the Traumatology outpatient clinics of the Hospital Clinico San Carlos (Madrid, Spain), were recruited, between October 2007, and May 2009. Demographic (gender, age), clinical [age at pain onset, age at OA disease diagnosis, body mass index (BMI), WOMAC score] and radiographic [Kellgren and Lawrence radiographic grade (KL)] variables were collected at baseline. Patients were followed up until death or November the 1st, 2013, and clinical records were examined for total joint replacement (TJR). Time at risk for each joint (right and left knee/hip) comprised the elapsed time between inclusion in the study and TJR, death or November the 1st, 2013. Survival techniques were used to estimate the incidence ratio (IR) of TJR, expressed per 1000 joint-years with 95% confidence interval [95%CI]. Cox bivariate and multivariate regression models were conducted to examine the risk factors for TJR. Proportionality of the models was tested using the Schoenfeld and the scaled Schoenfeld residuals. Results were expressed as hazard ratios (HRs) with [95% CIs]. Results: 194 subjects were included in the study (follow-up of 3596 joint-years). Therewere 74 total joint replacements, in 63 patients, with an IR of 21 per 1000 patient-year [95% confidence interval 16–26]. IR for knee and hip TJR were 36 [28–46], and 8 [5–13], respectively. IR was higher in the subjects recruited at the Traumatology outpatient clinic (30 [23–40] vs. 11 [7–17], p 1⁄4 0.0001). Moreover, those patients had higher baseline total WOMAC score (median 51 (inter-quartile rank 33– 63) vs. 34 (26–42), p < 0.0001), BMI (30.80 (26.67–33.30) vs. 28.72 (25.59–31.07), p 1⁄4 0.0033), and previous contra lateral TJR (10.68% vs. 1.10%, p 1⁄4 0.003). Proportion of subjects with KL grade III–IV was also higher in the Traumatology group (19.42% vs. 7.69%, p 1⁄4 0.060). In the multivariate analysis, predictors of joint replacement were previous TJR of the contra lateral joint (HR 3.02 [1.39–6.58], p1⁄4 0.005), baseline KL (I versus 0: HR 1.06 [0.07–15.43], p1⁄4 0.966, II vs. 0: HR 2.74 [0.81–9.25], p 1⁄4 0.105, III vs. 0: HR 9.94 [3.94–24.54], p1⁄4 9.50 10 7, IV vs. 0: HR 17.26 [7.24–41.16], p 1⁄4 1.33 10 10), and total WOMAC score (HR: 1.03 [1.01– 1.04], p 1⁄4 0.002), adjusted by gender, age and outpatient clinic when and where the patient was recruited, BMI, and joint analyzed. Although baseline KL of the contra lateral joint, BMI, and place of recruitment (Traumatology vs. Rheumatology) were also associated with higher rate of joint replacement in the bivariate analysis, no association was observed in the multivariate analysis. Conclusions: Presence of TJR of the knee or hip is a risk factor for future replacement of the contra lateral joint, regardless the extent of the basal radiological damage, and clinical status of the patient. 324 THE ASSOCIATION BETWEEN KNEE CONFIDENCE AND MUSCLE POWER, HOP PERFORMANCE, AND MOVEMENT QUALITY IN PEOPLE WITH ANTERIOR CRUCIATE LIGAMENT INJURY AT HIGH RISK OF KNEE OSTEOARTHRITIS E. Ageberg y, E.M. Roos z. y Lund Univ., Lund, Sweden; zUniv. of Southern Denmark, Odense, Denmark Purpose: To investigate associations between self-reported knee confidence and muscle power, hop performance, and movement quality, in patients with anterior cruciate ligament (ACL) injury at high risk of knee osteoarthritis. Methods: Cross-sectional data from 54 patients (mean age 30 years, range 20–39, 28% women) with an ACL injury, treated with rehabilitation with or without addition of reconstructive surgery, assessed 3 years (SD 0.9) after injury was used. The dependent variable was the patient’s reported trouble with lack of knee confidence on a 5-point Likert scale from the Knee injury and Osteoarthritis Outcome Score (KOOS), scored from 0 (no at all) to 4 (extremely troubled). Independent variables included 3 muscle power tests (knee extension, knee flexion, leg press), 3 hop performance tests (vertical jump, one-leg hop, side hop), and 5 tasks resembling daily activities (body-weight-altering test, single-limb mini squat, tiptoe standing single-limb mini squat, forward lunge, and mini-squat) for the assessment of movement quality, in terms of visual observation of the position of joints in relation to each other and the environment. The absolute value, and the Limb Symmetry Index (LSI, injured leg divided by uninjured and multiplied by 100) value, were used formuscle power and hop tests. A lower absolute value and a lower LSI (larger side-to-side difference) indicate worse muscle function. For movement quality, the total score for all five tasks on the injured side, the total score for the position of the knee relative to the foot on the injured side, the total score for displacement of the hip on the injured side, and the absolute difference in total score between injured and uninjured sides were used in the analysis. A higher total score and a larger side-to-side difference indicate worse movement quality. Spearman’s rank correlation analysis was used to test the association between knee confidence and muscle power, hop performance, and movement quality. Correlations with p-values <0.25 were included in the multivariate ordinal regression model with the negative log-log link. Results: Sixteen (29.6%) patients reported no trouble with lack of confidence in their knee. Twenty-four (44.4%) were mildly troubled, 10 (18.5%) moderately troubled, 3 (5.6%) severely troubled and 1 (1.9%) extremely troubled with lack of confidence in the knee. Those who scored that they were severely or extremely troubled were combined in the analysis (n 1⁄4 4). Significant associations were found between worse knee confidence and lower vertical jump height for the injured leg (rs 1⁄4 0.215, p 1⁄4 0.119), higher side-to-side difference (lower LSI) for knee extension power (rs 1⁄4 0.340, p 1⁄4 0.012), side hop (rs 1⁄4 0.330, p 1⁄4 0.015), and vertical jump (rs 1⁄4 0.351, p 1⁄4 0.009). Worse knee confidence was also associated with worse movement quality in terms of higher total score for all tasks for the injured side (rs 1⁄4 0.424, p 1⁄4 0.002), higher total score for knee position (rs 1⁄4 0.399, p 1⁄4 0.003) and hip position (rs 1⁄4 0.183, p1⁄4 0.189) for the injured leg. In the multivariate analysis, a larger side-to-side difference for the vertical jump (estimate 0.031, 95% CI 0.060 to 0.001, p1⁄4 0.043) and the side hop (estimate 0.022, 0.039 to 0.005, p 1⁄4 0.012) remained in the model. The model accounted for 25% of the variation in perceived knee confidence (Negelkerke R2 1⁄4 0.250). Conclusions: A larger side-to-side difference (lower LSI) in the vertical jump and the side hop are associated with worse knee confidence at a mean of 3 years after ACL injury. Altered movement quality during the performance of tasks resembling daily activities did not add any additional information. This suggests that the final phase of treatment should target exercises aiming at reducing side-to-side differences for demanding tasks, such as single-limb jumping, to improve knee confidence in people with ACL injury. 325 CHANGES IN STATIC AND DYNAMIC KNEE EXTENSOR STRENGTH AFTER TKA A.R. Marmon, L. Snyder-Mackler. Univ. of Delaware, Newark, DE, United