Quadriceps rate of torque development predicts disability in individuals with tibiofemoral knee osteoarthritis

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Abstracts / Osteoarthritis and Cartilage 25 (2017) S76eS444

Kellgren-Lawrence (KL) grades of knee osteoarthritis and mechanical knee alignment were associated with JSW measurements at 5 years. We hypothesized that patients with knee osteoarthritis as defined by KL grading and varus mechanical alignment would demonstrate narrower JSW than those without knee osteoarthritis and those with neutral or valgus alignment. Methods: Eighty-three athletes with an acute, isolated ACL injury who participated in cutting and pivoting activities prior to injury were included. Weightbearing posterior-anterior bent knee radiographs were completed at 5 years and analyzed using SigmaView software (Agfa HealthCare Corporation, Greenville, SC) to determine JSW, KL grades, and mechanical alignment in the medial tibiofemoral compartment of each limb. JSW was measured at a minimum and at a fixed location in each medial tibiofemoral joint (25% of distance from medial to lateral edge of femur (JSW.25)). Interlimb differences in JSW measures were calculated (involved minus uninvolved). Offsets (2
for women, 4
for men) were added to anatomical alignment measures to estimate the mechanical alignment of the knee. The offsets used have previously been shown to be reliable in calculating mechanical alignment from full limb films. Mechanical alignment for each patient was categorized as varus alignment ( < 2
), neutral alignment (between 2
and þ2
), or valgus alignment ( > þ2
). An independent t-test was used to determine if JSW measurements differed between those with and without medial osteoarthritis as defined by KL grades. A one-way analyses of variance (ANOVA) was used to determine if mechanical alignment was associated with JSW measurements. Results: The average age of the 83 patients at 5 years was 35.0 ± 11.8 years, 39% were women, and 23% were managed non-operatively. Patients completed radiographs an average 5.3 ± 0.7 years after ACL reconstruction or completion of non-operative rehabilitation. The average medial compartment minimum JSW was 4.8 ± 1.2 mm in the involved knee and 4.9 ± 1.0 mm in the contralateral knee. The average JSW.25 was 6.4 ± 1.3 mm in the involved knee and 6.3 ± 1.1 mm in the contralateral knee. Fourteen percent of the 83 patients had a KL grade of 2 or greater in the medial compartment of the involved knee at 5 years. The medial minimum JSW in the involved knee of patients with a KL grade of 2 or greater (OA) was 0.5 millimeters smaller than the uninvolved knee but 0.1 millimeters larger in patients with a KL grade of 0 or 1 (nonOA) (p: 0.115, OA: 0.5 ± 1.8 mm, nonOA: 0.1 ± 1.0 mm). Interlimb differences in JSW.25 did not differ between those with and without OA (p: 0.611, OA: 0.1 ± 1.6 mm, nonOA: 0.2 ± 0.8 mm). Fiftyeight percent of patients demonstrated radiographically neutral alignment at 5 years, 22% demonstrated varus alignment, and 20% demonstrated valgus alignment. Mechanical alignment was not associated with the interlimb difference in minimum JSW (p: 0.511, Varus: 0.2 ± 1.3 mm, Neutral: 0.1 ± 1.2 mm, Valgus: 0.2 ± 1.0 mm) or JSW.25 (p: 0.756, Varus: 0.1 ± 0.9 mm, Neutral: 0.2 ± 1.0 mm, Valgus: 0.3 ± 0.9 mm). Conclusions: Patients with advanced radiographic signs of post-traumatic knee osteoarthritis after ACL injury (KL grade of 2 or greater) demonstrated joint space narrowing while JSW was similar to the contralateral limb in patients without osteoarthritis. Knee malalignment did not correspond to JSW in the ACL-injured knee at 5 years; however, its long-term influence on post-traumatic knee osteoarthritis progression is not known. Recognition of the long-term effects of malalignment on knee joint health may affect surgical decisions to use alignment-modifying procedures such as osteotomies after ACL injury. 592 LOSS OF ANTERIOR CRUCIATE LIGAMENT INTEGRITY AND THE RISK OF SECONDARY MENISCAL INJURY AND BONE MARROW LESIONS: DATA FROM THE OSTEOARTHRITIS INITIATIVE V.L. Johnson y, A. Guermazi z, F.W. Roemer x, D.J. Hunter y. y The Univ. of Sydney, Sydney, Australia; z Quantitative Imaging Ctr., Dept. of Radiology, Boston Univ. Sch. of Med., Boston, MA, USA; x Dept. of Radiology, Univ. of Erlangen-Nuremberg, Germany, Erlangen, Germany Purpose: The aim was to determine differences in regard to patterns of meniscal damage (type and location) and bone marrow lesions (BMLs) between subjects with knee OA and prevalent ACL tears and those without tears. Methods: 600 participants (37 with either a complete or partial ACL tear) from the Osteoarthritis Initiative (OAI) study were included. Regional meniscal morphometry measures as well as semi-quantitative scoring of MRI using MRI OA Knee Scores (MOAKS) for the location of

meniscal tears and BMLs in index knees were compared between those with and without ACL tears. Chi-square tests were used to compare the prevalence of meniscal damage and BMLs. Results: 37 individuals with an ACL tear (40% female, average age ¼ 60.7years, BMI ¼ 31.0 kg/m2) displayed increased damage in the anterior regions of the medial meniscus (p-values ¼ 0.002) and the posterior lateral meniscus (p-value ¼ 0.03) when compared to individuals without an ACL tear (60% female, average age ¼ 61.5 years, BMI ¼ 30.7 kg/m2). Horizontal meniscal tears were the most common type of meniscal damage. Individuals with an ACL tear showed large BMLs which were significantly associated with meniscal damage in the anterior medial meniscus and central lateral meniscus (p-values ¼ 0.02 and 0.004 respectively) whilst complex, radial or vertical tears were significant in the medial central and lateral posterior menisci (both pvalues 0.002). Conclusions: Overall, our study found that BMLs were associated with ipsi-compartmental meniscal damage in the medial tibiofemoral compartment amongst individuals with an ACL tear and had a concomitant partial maceration or horizontal meniscal tear. Vertical, radial and complex meniscal tears were identified more prominently in the medial meniscal body and posterior portions of the lateral meniscus. These tears, however, were not associated with BMLs with not one of these tears being accompanied by an underlying BML regardless of whether an individual had suffered an ACL tear or not. Clinically the importance of these findings are that meniscal maceration, complex tears and degenerative horizontal tears are more frequently displayed in the medial compartment, particularly the central and anterior meniscal horns, and are associated with an increased risk of medial meniscal extrusion. Further to this degenerative meniscal tears have been associated not only with an increase risk in underlying BML development but also a worse long-term prognosis. Current evidence strongly suggests that degenerative meniscus tears generally occur in knees already compromised by changes that may represent incident radiographic OA. Thus in accordance with our study, a horizontal degenerative tear or complete or partial maceration of the meniscus may project regionspecific OA disease progression and severity. This is significant as it may represent a possible opportunity for early intervention. Asymptomatic individuals that display MRI meniscal damage represent a cohort who could be targeted for drug interventions that could prevent the incidence of structural damage, such as the occurrence of BMLs and in turn, hopefully prevent the development of symptomatic OA. Individuals with prevalent knee OA and an ACL tear displayed an increased risk of BML incidence with region-specific horizontal medial meniscal tears or medial meniscus partial maceration. However, the overall pattern of joint damage exhibited between the two cohorts was not significantly different. 593 QUADRICEPS RATE OF TORQUE DEVELOPMENT PREDICTS DISABILITY IN INDIVIDUALS WITH TIBIOFEMORAL KNEE OSTEOARTHRITIS B.A. Luc-Harkey y, H.C. Davis y, M.S. Harkey y, M.R. Laffan y, C.M. Rizk y, B.R. Gaynor z, E.D. Ryan y, J.T. Blackburn y, D.B. Nissman y, J.T. Spang y, B. Pietrosimone y. y Univ. of North Carolina at Chapel Hill, Chapel Hill, NC, USA; z Univ. of Washington, Seattle, WA, USA Purpose: Knee osteoarthritis (OA) is the leading musculoskeletal cause of years lived with disability. While maintaining quadriceps strength is imperative for limiting disability, many activities of daily living (i.e. rising from sitting, ascending stairs) also require rapid force generation, quantified as rate of torque development (RTD), rather than strength alone. Quadriceps RTD may also influence disability in individuals with knee OA. As quadriceps strength declines as the disease progresses, quadriceps RTD may influence disability differently depending upon radiographic OA disease severity. Determining if quadriceps RTD influences disability in individuals with knee OA would identify a specific therapeutic target for interventions aiming to reduce disability. Our purpose was to determine if quadriceps RTD predicts disability in individuals with knee OA after accounting for quadriceps strength. Secondarily, we separately determined if quadriceps RTD predicts disability in those with mild-moderate bilateral knee OA and moderatesevere bilateral knee OA. Methods: Forty-seven individuals (55% female; 62.7 ± 6.7 years; 172.3 ± 9.1 cm; 82.8 ± 15.8 kg) with symptomatic knee OA, defined as K-L score of 2e4 and normalized WOMAC function score 31, were

Abstracts / Osteoarthritis and Cartilage 25 (2017) S76eS444

included. Disability outcome measures included self-reported function assessed via the WOMAC function subscale, and three measures of physical performance including: 1) 20-meter fast paced walk (WALK), 2) 30-second chair stand (CHAIR), and 3) timed stair climb (STAIR). Quadriceps strength and RTD were assessed during a maximal isometric contraction at 70
on an isokinetic dynamometer. Quadriceps strength was defined as the peak torque value, and RTD was calculated as the slope of the torque-time curve at various time intervals following torque onset (RTD0e30 ms, RTD0e50 ms, RTD50e100 ms, RTD100e200 ms). Early and late RTD intervals were used to assess neural and structural components of RTD, respectively. Quadriceps strength and RTD were calculated for the involved (i.e more symptomatic) and uninvolved limb. Pearson product moment correlations were used to assess bivariate associations between each measure of disability and quadriceps strength and quadriceps RTD. If a quadriceps RTD outcome significantly associated with a measure of disability a linear regression model was used to determine the unique contribution of quadriceps RTD to the specific measure of disability after accounting for quadriceps strength. After adding quadriceps strength into the regression model, the change in R2 (DR2) for the RTD outcome was determined. Participants were then separated into two groups based on bilateral disease severity, which was determined by summing bilateral K-L scores. Individuals with a total K-L score  5 were classified as mild-moderate bilateral OA. Individuals with a total K-L score  6 were classified as moderate-severe bilateral OA; this ensured both limbs were at least a KL grade of 3. The previous statistical analysis was utilized again within each severity group. Alpha level was set a priori (P  0.05). Results: In the entire cohort, involved limb RTD100e200 significantly predicted 7% of WALK (DR2 ¼ 0.074; P ¼ 0.028). In the entire cohort, uninvolved limb RTD0e50 significantly predicted 15% (DR2 ¼ 0.148; P ¼ 0.003) of CHAIR; RTD50e100 significantly predicted 12% (DR2 ¼ 0.122; P ¼ 0.008) and 8% (DR2 ¼ 0.077; P ¼ 0.035) of WALK and CHAIR, respectively; RTD100e200 significantly predicted 8% (DR2 ¼ 0.079; P ¼ 0.037) and 7% (DR2 ¼ 0.074; P ¼ 0.050) of WALK and CHAIR, respectively. In the mild-moderate cohort uninvolved limb RTD0e30 significantly predicted 22% (DR2 ¼ 0.217; P ¼ 0.038) and 28% (DR2 ¼ 0.275; P ¼ 0.006) in WOMAC and CHAIR, respectively; RTD0e50 significantly predicted 32% (DR2 ¼ 0.320; P ¼ 0.002) in CHAIR; RTD50e100 significantly predicted 18% (DR2 ¼ 0.184; P ¼ 0.030) in CHAIR. None of the quadriceps RTD measures significantly predicted any outcome of disability in the cohort of participants with moderate-severe bilateral OA after accounting for quadriceps strength (P > 0.05). Conclusions: In individuals with knee OA, quadriceps RTD significantly predicts various measures of disability after accounting for quadriceps strength. Interestingly, quadriceps RTD predicted the greatest amount of unique variance in disability in the mild-moderate bilateral OA group, but quadriceps RTD did not predict disability in the moderate-severe group. Interventions to decrease disability may need to be specific to radiographic disease severity; improving quadriceps RTD may be beneficial for decreasing disability in individuals in the early stages of radiographic disease. 594 VASTUS MEDIALIS INTRAMUSCULAR FAT IS ASSOCIATED WITH INCREASE IN MRI DEGENERATION OF THE KNEE OVER 3-YEARS D. Kumar y, T.M. Link z, S. Majumdar z, R.B. Souza z. y Boston Univ., Boston, MA, USA; z Univ. of California, San Francisco, San Francisco, CA, USA Purpose: To evaluate the association of fatty infiltration of vastus medialis (VM) with knee degeneration over 3-years. Methods: We studied subjects (n ¼ 69) with and without radiographic knee osteoarthritis (OA) over 3-years. All subjects underwent 3.0 Tesla MRI at baseline (BL) and 3-years (3Y) later. At baseline, chemical shiftbased water/fat images were used to quantify the intramuscular fat fraction and the lean anatomical cross-sectional area (LACSA) for the VM and other quadriceps muscles (vastus lateralis, vastus intermedius, rectus femoris). An experienced radiologist performed paired readings of high-resolution 3D fast spin echo knee images at BL and 3Y using modified Whole Organ Magnetic Resonance Scoring of Osteoarthritis (mWORMS) grading of lesions in the articular cartilage, meniscus, and bone marrow lesion (BML). Subjects who showed an increase in knee cartilage, meniscus or BML scores from BL to 3Y were identified. The score at 3Y had to be > 1 for cartilage or meniscus lesions to only identify subjects with morphological lesions rather than signal change.

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We used logistic regression to assess if baseline VM fat fraction and LACSA identified subjects with increase in mWORMS scores. Results: Overall 43/69 subjects had an increase in either cartilage (26/ 43), meniscus (19/43), or BML (22/43) scores over 3-years. Compared to the subjects who did not show an increase in mWORMS scores, the subjects who showed an increase were older (no increase: 47.8 ± 10.8 years, increase: 56.6 ± 8.2 years, p < 0.0001), had larger proportion of females (no increase: 8/26 females, increase: 28/43 females, p ¼ 0.007) and had a larger proportion of people with radiographic knee OA (no increase: 2/26 with OA, increase: 22/43 with OA, p < 0.0001). At baseline, VM fat fraction was higher (unadjusted p < 0.0001) in subjects with increase in mWORMS scores (7.7 ± 2.2%) compared to those with no increase (5.7 ± 1.8%); the VM LACSA was smaller but not significant (unadjusted p ¼ 0.095) in subjects with increase in mWORMS (10.8 cm2) compared to those with no increase (12.3 cm2). Longitudinal logistic regression showed that in all subjects, VM fat fraction was associated with an odds ratio (OR) of 1.83 (p ¼ 0.024) for increase in knee degeneration scores over 3-years after adjustment for age, sex, BMI, and presence of radiographic OA. The association of VM LACSA with increase in knee degeneration over 3-years was not significant (p ¼ 0.618). Fat fraction of the quadriceps muscle (p ¼ 0.114) as a whole (weighted average of VM and other quadriceps muscles) and LACSA of the quadriceps muscle (p ¼ 0.443) did not have significant association with increase in knee mWORMS scores over 3-years after adjusting for age, BMI, sex, and presence of radiographic knee OA. Conclusions: Our results demonstrate that each % increase in fatty infiltration of the vastus medialis muscle is associated with an 83% higher risk of MRI degeneration of the knee over 3-years. Our previous cross-sectional analyses had demonstrated that people with radiographic knee OA have greater fatty infiltration of the quadriceps muscle compared to people without radiographic knee OA, and that fatty infiltration of the quadriceps was associated with worse symptomatic and structural severity of knee OA. The longitudinal results from this study advance our previous findings and lend support to the role of muscle adiposity in knee OA progression. These findings suggest that of the quadriceps muscles VM may have greater involvement in the knee OA disease process. Fatty infiltration of the VM can potentially be reduced by exercise interventions and may be effective at slowing degeneration of the knee. Furthermore, our results demonstrate the importance of VM adiposity over VM size in progression of knee degeneration, and as a potential target for exercise interventions. 595 ARTHROSCOPIC REPAIR OF BUCKET-HANDLE MENISCUS TEARS: A DESCRIPTION OF PATIENT DEMOGRAPHICS AND A COMPARISON OF PATIENTS WITH AND WITHOUT POSTOPERATIVE RE-TEAR E.J. Cotter, K.C. Wang, B.M. Saltzman, A.B. Yanke, B. Forsythe, N.N. Verma, B.J. Cole. Midwest Orthopaedics at RUSH, Chicago, IL, USA Purpose: The purpose of this study was to evaluate a single academic institution’s cohort of patients with bucket-handle meniscus tears (BHMT) who underwent arthroscopic repair. Specifically, we sought to (1) report patient demographic information and (2) compare the subgroup of patients with successful outcomes or failure after repair. Methods: Consecutive patients undergoing arthroscopic repair of a bucket-handle meniscus tear at a single academic institution between January 1, 2005 and August 1, 2016 were retrospectively evaluated. Preoperative demographics (age, body mass index [BMI], gender, smoking status, pre-injury sports level, symptom duration, prior meniscal surgery) and radiographic joint space narrowing were obtained. Intraoperative data including meniscus laterality, zone of repair, repair technique, and concomitant procedures were noted. Postoperative rates of meniscal re-tear were obtained. Patients with and without re-tear were compared using Student’s t-test and chi-squared test to identify differences in demographic or intraoperative characteristics. A p-value < 0.05 was considered statistically significant. Results: A total of 138 patients were identified and followed for a mean 6.25 ± 6.70 months postoperatively. The mean age and BMI were 25.9 ± 10.36 years and 25.68 ± 5.44 kg/m2, respectively, and 15.2% identified as high-level athletes. Patients experienced symptoms for a mean 3.96 ± 9.84 months prior to surgery. 85 (61.6%) patients had medial and 53 (38.4%) had lateral BHMTs. Ninety (65.2%) patients were male,130 (94.2%) were non-smokers, 133 (96.3%), were primary meniscal repairs and 107 (86.3%) did not have preoperative joint space narrowing in the affected