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Context: Analyses of the path of instant center of rotation (PICR) can be used to infer joint-surface rolling and sliding motion (arthrokinematics). Previous PICR research has not quantified arthrokinematics during weight-bearing (WB) movement conditions or studied the association of muscle activity with arthrokinematics. Objective: To examine tibiofemoral arthrokinematics and thigh-muscle EMG during WB and non-weight-bearing (NWB) movement. Design: 2 × 9 repeated-measures experiment. Setting: Laboratory. Participants: 11 healthy adults (mean age 24 years). Main Outcome Measures: Tibiofemoral percentage rolling arthrokinematics and quadriceps: hamstring EMG activity. Results: WB percentage rolling (76.0% ± 4.7%) exceeded that of NWB (57.5% ± 1.8%) through terminal knee extension (F[sub 8,80] = 8.99, P < .001). Quadriceps:hamstring EMG ratios accounted for 45.1% and 34.7% of the variance in arthrokinematics throughout the WB and NWB movement conditions, respectively (P < .001 ). Conclusions: More joint-surface rolling occurs through terminal knee extension during WB movement and is associated with an increase in hamstring activity. [ABSTRACT FROM AUTHOR]

Background: While a primary goal of anterior cruciate ligament (ACL) reconstruction is to reduce pathologically increased anterior and rotational knee laxity, the relationship between knee laxity after ACL reconstruction and patient-reported knee function remains unclear. Hypothesis: There would be no significant correlation between the degree of residual anterior and rotational knee laxity and patient-reported outcomes (PROs) 2 years after primary ACL reconstruction. Study Design: Cross-sectional study; Level of evidence, 3. Methods: From a prospective multicenter nested cohort of patients, 433 patients younger than 36 years of age injured in sports with no history of concomitant ligament surgery, revision ACL surgery, or surgery of the contralateral knee were identified and evaluated at a minimum 2 years after primary ACL reconstruction. Each patient underwent Lachman and pivot-shift evaluation as well as a KT-1000 arthrometer assessment along with Knee injury and Osteoarthritis Outcome Score and subjective International Knee Documentation Committee (IKDC) scores. A proportional odds logistic regression model was used to predict each 2-year PRO score, controlling for preoperative score, age, sex, body mass index, smoking, Marx activity score, education, subsequent surgery, meniscal and cartilage status, graft type, and range of motion asymmetry. Measures of knee laxity were independently added to each model to determine correlation with PROs. Results: Side-to-side manual Lachman differences were IKDC A in 246 (57%) patients, IKDC B in 183 (42%) patients, and IKDC C in 4 (<1%) patients. Pivot-shift was classified as IKDC A in 209 (48%) patients, IKDC B in 183 (42%) patients, and IKDC C in 11 (2.5%) patients. The mean side-to-side KT-1000 difference was 2.0 ± 2.6 mm. No significant correlations were noted between pivot-shift or anterior tibial translation as assessed by Lachman or KT-1000 and any PRO. All predicted differences in PROs based on IKDC A versus B pivot-shift and anterior tibial translation were less than 4 points. Conclusion: Neither the presence of IKDC A versus B pivot-shift nor increased anterior tibial translation of up to 6 mm is associated with clinically relevant decreases in PROs 2 years after ACL reconstruction. [ABSTRACT FROM AUTHOR]

Background: Knee laxity in the setting of anterior cruciate ligament (ACL) injury is often assessed through physical examination using the Lachman, pivot shift, and anterior drawer tests. The degree of laxity noted on these examinations may influence treatment decisions and prognosis. Hypothesis: Increased preoperative knee laxity is associated with increased risk of revision ACL reconstruction, increased risk of contralateral ACL reconstruction, and poorer patient-reported outcomes at 6 years postoperatively. Study Design: Cohort study; Level of evidence, 2. Methods: 2333 patients who underwent primary isolated ACL reconstruction without additional ligament injury were identified. Patients reported by the operating surgeons to have an International Knee Documentation Committee (IKDC) grade D Lachman, anterior drawer, or pivot shift examination were classified as having a high-grade laxity. Multiple logistic regression models were used to evaluate whether having high-grade preoperative laxity was predictive of increased odds of undergoing subsequent revision or contralateral ACL reconstruction within 6 years of the index procedure, controlling for patient age, sex, body mass index, Marx activity level, sport, graft type, medial meniscal treatment, and lateral meniscal treatment. Multiple linear regression modeling was used to evaluate whether having high-grade preoperative laxity was predictive of poorer IKDC or Knee injury and Osteoarthritis Outcome Score Knee-Related Quality of Life (KOOS-QOL) scores at 6 years postoperatively, after controlling for baseline score, patient age, ethnicity, sex, body mass index, marital status, smoking status, sport participation, competition level, Marx activity rating score, graft type, and articular cartilage and meniscal status. Results: In total, 743 of 2325 patients (32.0%) were noted to have high-grade laxity on at least 1 physical examination test. High-grade Lachman was noted in 334 patients (14.4%), high-grade pivot shift was noted in 617 patients (26.5%), and high-grade anterior drawer was noted in 233 patients (10.0%). Six-year revision and contralateral ACL reconstruction data were available for 2129 patients (91.6%). High-grade prereconstruction Lachman was associated with significantly increased odds of ACL graft revision (odds ratio [OR], 1.76; 95% CI, 1.10-2.80, P = .02) and contralateral ACL reconstruction (OR, 1.68; 95% CI, 1.09-2.69; P = .019). High-grade prereconstruction pivot shift was associated with significantly increased odds of ACL graft revision (OR, 1.75; 95% CI, 1.19-2.54, P = .002) but not with significantly increased odds of contralateral ACL reconstruction (OR, 1.30; 95% CI, 0.89-1.87; P = .16). High-grade prereconstruction laxity was associated with statistically significantly lower 6-year IKDC (β = −2.26, P = .003), KOOS-QOL (β = −2.67, P = .015), and Marx activity scores (β = −0.54, P = .020), but these differences did not approach clinically relevant differences in patient-reported outcomes. Conclusion: High-grade preoperative knee laxity is predictive of increased odds of revision ACL reconstruction and contralateral ACL reconstruction 6 years after ACL reconstruction. Poorer patient-reported outcome scores in the high-grade laxity group were also noted, but the difference did not reach a level of clinical relevance. [ABSTRACT FROM AUTHOR]

Background: The Knee injury and Osteoarthritis Outcome Score (KOOS) has demonstrated inferior psychometric properties when compared with the International Knee Documentation Committee (IKDC) subjective knee form when assessing outcomes after anterior cruciate ligament (ACL) reconstruction. The KOOS, Joint Replacement (KOOS, JR) is a validated short-form instrument to assess patient-reported outcomes (PROs) after knee arthroplasty, and the purpose of this study was to determine if augmenting the KOOS, JR with additional KOOS items would allow for the creation of a short-form KOOS-based global knee score for patients undergoing ACL reconstruction, with psychometric properties similar to those of the IKDC. Hypothesis: An augmented version of the KOOS, JR could be created that would demonstrate convergent validity with the IKDC but avoid the ceiling effects and limitations previously noted with several of the KOOS subscales. Study Design: Cohort study (diagnosis); Level of evidence, 2. Methods: Based on preoperative and 2-year postoperative responses to the KOOS questionnaires from a sample of 1904 patients undergoing ACL reconstruction, an aggregate score combining the KOOS, JR and the 4 KOOS Quality of Life subscale questions, termed the KOOSglobal, was developed. Psychometric properties of the KOOSglobal were then compared with those of the IKDC subjective score. Convergent validity between the KOOSglobal and IKDC was assessed with a Spearman correlation (ρ). Responsiveness of the 2 instruments was assessed by calculating the pre- to postoperative effect size and relative efficiency. Finally, the presence of a preoperative floor or postoperative ceiling effect was defined with the threshold of 15% of patients reporting either the worst possible (0 for KOOSglobal and IKDC) or the best possible (100 for KOOSglobal and IKDC) scores, respectively. Results: The newly developed KOOSglobal was responsive after ACL reconstruction and demonstrated convergent validity with the IKDC. The KOOSglobal significantly correlated with the IKDC scores (ρ = 0.91, P < .001), explained 83% of the variability in IKDC scores, and was similarly responsive (relative efficiency = 0.63). While there was a higher rate of perfect postoperative scores with the KOOSglobal (213 of 1904, 11%) than with the IKDC (6%), the KOOSglobal was still below the 15% ceiling effect threshold. Conclusion: The large ceiling effects limit the ability to use several of the KOOS subscales with the younger, more active ACL population. However, by creating an aggregate score from the KOOS, JR and 4 KOOS Quality of Life subscale questions, the 11-item KOOSglobal offers a responsive PRO tool after ACL reconstruction that converges with the information captured with the IKDC. Also, by offering the ability to calculate multiple scores from a single questionnaire, the KOOSglobal may provide the orthopaedic community a single PRO platform to be used across knee-related subspecialties. Registration: NCT00478894 (ClinicalTrials.gov identifier). [ABSTRACT FROM AUTHOR]

Background: Anterior cruciate ligament (ACL) reconstruction can effectively return athletes to the playing field, but they are still at risk of developing posttraumatic osteoarthritis (PTOA). No studies have used multivariable analysis to evaluate the predictors of radiographic PTOA in the lateral compartment of the knee at short-term follow-up after ACL reconstruction. Purpose: To determine the predictors of radiographic joint space narrowing in the lateral compartment 2 to 3 years after ACL reconstruction in a young, active cohort. Study Design: Cohort study; Level of evidence, 2. Methods: A nested cohort of 358 patients from the Multicenter Orthopaedic Outcomes Network (MOON) prospective cohort who were aged ≤33 years, were injured playing a sport, and had never undergone surgery on the contralateral knee were followed up 2 years after ACL reconstruction with questionnaires and with weightbearing knee radiographs using the metatarsophalangeal (MTP) joint technique. The joint space width in the lateral compartment was measured using a semiautomatic computerized method, and multivariable predictive modeling was used to evaluate the relationship between meniscus treatment, cartilage injury, graft type, and joint space while adjusting for age, sex, body mass index, and Marx activity score. Results: The mean lateral joint space width was 0.11 mm narrower on the ACL-reconstructed knee compared with the contralateral healthy knee (7.69 mm vs 7.80 mm, respectively; P < .01). Statistically significant predictors of a narrower joint space width on the ACL-reconstructed knee included lateral meniscectomy (P < .001) and a Marx activity score less than 16 points (P < .001). Conclusion: This study identifies lateral meniscectomy and a lower baseline Marx activity score to be predictors of radiographic joint space narrowing in the lateral compartment 2 to 3 years after ACL reconstruction in young, active patients without a prior knee injury. [ABSTRACT FROM AUTHOR]

Background: The long-term prognosis and risk factors for quality of life and disability after anterior cruciate ligament (ACL) reconstruction remain unknown. Hypothesis/Purpose: Our objective was to identify patient-reported outcomes and patient-specific risk factors from a large prospective cohort at a minimum 10-year follow-up after ACL reconstruction. We hypothesized that meniscus and articular cartilage injuries, revision ACL reconstruction, subsequent knee surgery, and certain demographic characteristics would be significant risk factors for inferior outcomes at 10 years. Study Design: Therapeutic study; Level of evidence, 2. Methods: Unilateral ACL reconstruction procedures were identified and prospectively enrolled between 2002 and 2004 from 7 sites in the Multicenter Orthopaedic Outcomes Network (MOON). Patients preoperatively completed a series of validated outcome instruments, including the International Knee Documentation Committee (IKDC), Knee injury and Osteoarthritis Outcome Score (KOOS), and Marx activity rating scale. At the time of surgery, physicians documented all intra-articular abnormalities, treatment, and surgical techniques utilized. Patients were followed at 2, 6, and 10 years postoperatively and asked to complete the same outcome instruments that they completed at baseline. The incidence and details of any subsequent knee surgeries were also obtained. Multivariable regression analysis was used to identify significant predictors of the outcome. Results: A total of 1592 patients were enrolled (57% male; median age, 24 years). Ten-year follow-up was obtained on 83% (n = 1320) of the cohort. Both IKDC and KOOS scores significantly improved at 2 years and were maintained at 6 and 10 years. Conversely, Marx scores dropped markedly over time, from a median score of 12 points at baseline to 9 points at 2 years, 7 points at 6 years, and 6 points at 10 years. The patient-specific risk factors for inferior 10-year outcomes were lower baseline scores; higher body mass index; being a smoker at baseline; having a medial or lateral meniscus procedure performed before index ACL reconstruction; undergoing revision ACL reconstruction; undergoing lateral meniscectomy; grade 3 to 4 articular cartilage lesions in the medial, lateral, or patellofemoral compartments; and undergoing any subsequent ipsilateral knee surgery after index ACL reconstruction. Conclusion: Patients were able to perform sports-related functions and maintain a relatively high knee-related quality of life 10 years after ACL reconstruction, although activity levels significantly declined over time. Multivariable analysis identified several key modifiable risk factors that significantly influence the outcome. [ABSTRACT FROM AUTHOR]

Background: Football puts athletes at risk for knee injuries such meniscus and anterior cruciate ligament (ACL) tears, which are associated with the development of osteoarthritis (OA). Previous knee surgery, player position, and body mass index (BMI) may be associated with knee OA.Hypothesis: In elite football players undergoing knee magnetic resonance imaging at the National Football League's Invitational Combine, the prevalence of knee OA is associated with previous knee surgery and BMI.Study Design: Retrospective cohort.Level Of Evidence: Level 4.Methods: A retrospective review was performed of all participants of the National Football League Combine from 2005 to 2009 who underwent magnetic resonance imaging of the knee because of prior knee injury, surgery, or knee-related symptoms or concerning examination findings. Imaging studies were reviewed for evidence of OA. History of previous knee surgery-including ACL reconstruction, meniscal procedures, and articular cartilage surgery-and position were recorded for each athlete. BMI was calculated based on height and weight.Results: There was a higher prevalence of OA in knees with a history of previous knee surgery (23% vs 4.0%, P < 0.001). The prevalence of knee OA was 4.0% in those without previous knee surgery, 11% in those with a history of meniscus repair, 24% of those with a history of ACL reconstruction, and 27% of those with a history of partial meniscectomy. Among knees with a previous ACL reconstruction, the rate of OA doubled in tibiofemoral compartments in which meniscal surgery was performed. BMI >30 kg/m2 was also associated with a higher risk of OA ( P = 0.007) but player position was not associated with knee OA.Conclusions: Previous knee surgery, particularly ACL reconstruction and partial meniscectomy, and elevated BMI are associated with knee OA in elite football players. Future research should investigate ways to minimize the risk of OA after knee surgery in these athletes.Clinical Relevance: Treatment of knee injuries in football athletes should consider chondroprotection, including meniscal preservation and cartilage repair, when possible. [ABSTRACT FROM AUTHOR]

Background: Knee laxity in the setting of suspected anterior cruciate ligament (ACL) injury is frequently assessed through physical examination using the Lachman, pivot-shift, and anterior drawer tests. The degree of laxity noted on these examinations may influence treatment decisions and prognosis. Hypothesis: Increased preoperative knee laxity would be associated with increased risk of subsequent revision ACL reconstruction and worse patient-reported outcomes 2 years postoperatively. Study Design: Cohort study; Level of evidence, 2. Methods: From an ongoing prospective cohort study, 2333 patients who underwent primary isolated ACL reconstruction without collateral or posterior cruciate ligament injury were identified. Patients reported by the operating surgeons as having an International Knee Documentation Committee (IKDC) grade D for Lachman, anterior drawer, or pivot-shift examination were classified as having high-grade laxity. Multiple logistic regression modeling was used to evaluate whether having high-grade preoperative laxity was associated with increased odds of undergoing revision ACL reconstruction within 2 years of the index procedure, controlling for patient age, sex, Marx activity level, level of competition, and graft type. Multiple linear regression modeling was used to evaluate whether having high-grade preoperative laxity was associated with worse IKDC score or Knee injury and Osteoarthritis Outcome Score Knee-Related Quality of Life subscale (KOOS-QOL) scores at a minimum 2 years postoperatively, controlling for baseline score, patient age, ethnicity, sex, body mass index, marital status, smoking status, sport participation, competition level, Marx activity rating score, graft type, and articular cartilage and meniscus status. Results: Pre-reconstruction laxity data were available for 2325 patients (99.7%). Two-year revision data were available for 2259 patients (96.8%), and patient-reported outcomes were available for 1979 patients (84.8%). High-grade preoperative laxity was noted in 743 patients (31.9%). The mean postoperative IKDC score was 81.8 ± 15.9, and the mean KOOS-QOL score was 72.0 ± 22.0. The presence of high-grade pre-reconstruction laxity was associated with significantly increased odds of ACL graft revision (odds ratio [OR] = 1.87 [95% CI, 1.19-2.95]; P = .007). The presence of high-grade pre-reconstruction laxity was not associated with any difference in postoperative IKDC (β = −0.56, P = .44) or KOOS-QOL (β = 0.04, P = .97). Conclusion: The presence of high-grade pre-reconstruction knee laxity as assessed by manual physical examination under anesthesia is associated with significantly increased odds of revision ACL surgery but has no association with patient-reported outcome scores at 2 years after ACL reconstruction. [ABSTRACT FROM AUTHOR]

Background: Multiple techniques have been suggested for the treatment of isolated knee articular cartilage injuries. For smaller lesions (<2-5 cm2), microfracture and osteochondral autograft transplantation (OAT) are commonly used options. With an increasing focus on health care efficiency, analyzing the cost-effectiveness of treatment modalities has become increasingly important. Purpose/Hypothesis: The purpose of this study was to analyze the costs and outcomes of microfracture and OAT to compare their cost-effectiveness. The hypothesis was that microfracture would be more cost-effective. Study Design: Economic and decision analysis; Level of evidence, 2. Methods: A literature search was performed to identify studies comparing microfracture and OAT for the treatment of articular cartilage lesions of the distal femur in an adult population. Data from these studies including surgical time, failure rates, revision surgeries, outcome scores, and return to athletics were then incorporated into a constructed cost model using standard accounting methodology. The model was based on actual 2013 cost figures (in US dollars) for all procedure, operating room, and instrumentation costs. Results: Three studies, with a mean follow-up of 8.7 years, met the inclusion criteria of having evidence level 1 or 2 comparing microfracture and OAT. There was a cumulative 28.6% reoperation rate among patients undergoing microfracture compared with 12.5% among patients undergoing OAT. While both groups demonstrated significant improvements compared with preoperative levels, the only significant differences in any outcome score reported between the 2 procedures were the International Cartilage Repair Society (ICRS) score and patient-reported return to their previous sports activity level. While microfracture had a lower initial cost ($3100), these savings lessened over 1 year ($1843) and 10 years ($996). Microfracture was more cost-effective when comparing Lysholm and Hospital for Special Surgery scores, whereas OAT was more cost-effective when comparing Tegner and ICRS scores. There was a significantly lower cost for return to play in athletes after OAT versus microfracture at 1 year ($11,428 vs $16,953, respectively), 3 years ($12,856 vs $38,000, respectively), and 10 years ($32,141 vs $60,799, respectively). Conclusion: Published level 1 and 2 clinical studies with a 10-year follow-up demonstrated that the net cost and cost-effectiveness of microfracture and OAT are comparable for the treatment of isolated articular cartilage lesions of the distal femur. Clinical Relevance: Given similar clinical outcomes, microfracture and OAT are both viable, cost-effective first-line treatment options for these injuries. [ABSTRACT FROM AUTHOR]