Ingrid Eitzen

Preoperative quadriceps strength is a significant predictor of knee function two years after anterior cruciate ligament reconstruction

Objective: To identify preoperative predictive factors for knee function two years after reconstructive surgery of the anterior cruciate ligament (ACL). The main hypothesis was that preoperative quadriceps strength would be the most significant predictor for knee function two years after reconstructive surgery. Design: Cohort study. Setting: ACL injured individuals treated at a University Hospital and an outpatient clinic in Oslo, Norway. Participants: Seventy-three individuals with complete unilateral rupture of the ACL scheduled for reconstruction with a bone-patellar-bone autograft were included in the study, from where 60 were available for two-year follow up and included in the final analyses. Interventions: Not applicable. Main outcome measurements: Identification of baseline independent variables that may predict knee function assessed with the Cincinnati Knee Score as dependent variable two years after ACL reconstruction. Results: Quadriceps muscle strength, meniscus injury and the Short-Form-36 Bodily Pain sub score were identified as significant predictors for knee function assessed from the Cincinnati Knee Score two years after ACL reconstruction. Individuals with preoperative quadriceps strength deficits above 20% also had persistent significantly larger strength deficits two years after surgery. Conclusions: Preoperative quadriceps muscle strength deficits and meniscus injuries have significant negative consequences for the long-term functional outcome after ACL reconstruction. From our findings we suggest that ACL reconstruction should not be performed before quadriceps muscle strength deficits of the injured limb is less than 20% of the uninjured limb.

Single-legged hop tests as predictors of self-reported knee function after anterior cruciate ligament reconstruction: the Delaware-Oslo ACL cohort study.

Background: Single-legged hop tests are commonly used functional performance measures that can capture limb asymmetries in patients after anterior cruciate ligament (ACL) reconstruction. Hop tests hold potential as predictive factors of self-reported knee function in individuals after ACL reconstruction. Hypothesis: Single-legged hop tests conducted preoperatively would not and 6 months after ACL reconstruction would predict self-reported knee function (International Knee Documentation Committee [IKDC] 2000) 1 year after ACL reconstruction. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: One hundred twenty patients who were treated with ACL reconstruction performed 4 single-legged hop tests preoperatively and 6 months after ACL reconstruction. Self-reported knee function within normal ranges was defined as IKDC 2000 scores greater than or equal to the age- and sex-specific normative 15th percentile score 1 year after surgery. Logistic regression analyses were performed to identify predictors of self-reported knee function within normal ranges. The area under the curve (AUC) from receiver operating characteristic curves was used as a measure of discriminative accuracy. Results: Eighty-five patients completed single-legged hop tests 6 months after surgery and the 1-year follow-up with 68 patients classified as having self-reported knee function within normal ranges 1 year after reconstruction. The crossover hop and 6-m timed hop limb symmetry index (LSI) 6 months after ACL reconstruction were the strongest individual predictors of self-reported knee function (odds ratio, 1.09 and 1.10) and the only 2 tests in which the confidence intervals of the discriminatory accuracy (AUC) were above 0.5 (AUC = 0.68). Patients with knee function below normal ranges were over 5 times more likely of having a 6-m timed hop LSI lower than the 88% cutoff than those with knee function within normal ranges. Patients with knee function within normal ranges were 4 times more likely to have a crossover hop LSI greater than the 95% cutoff than those with knee function below normal ranges. No preoperative single-legged hop test predicted self-reported knee function within normal ranges 1 year after ACL reconstruction (all P > .353). Conclusion: Single-legged hop tests conducted 6 months after ACL reconstruction can predict the likelihood of successful and unsuccessful outcome 1 year after ACL reconstruction. Patients demonstrating less than the 88% cutoff score on the 6-m timed hop test at 6 months may benefit from targeted training to improve limb symmetry in an attempt to normalize function. Patients with minimal side-to-side differences on the crossover hop test at 6 months possibly will have good knee function at 1 year if they continue with their current training regimen. Preoperative single-legged hop tests are not able to predict postoperative outcomes.

A Progressive 5-Week Exercise Therapy Program Leads to Significant Improvement in Knee Function Early After Anterior Cruciate Ligament Injury

STUDY DESIGN Prospective cohort study without a control group. OBJECTIVES Firstly, to present our 5-week progressive exercise therapy program in the early stage after anterior cruciate ligament (ACL) injury. Secondly, to evaluate changes in knee function after completion of the program for patients with ACL injury in general and also when classified as potential copers or noncopers, and, finally, to examine potential adverse events. BACKGROUND Few studies concerning early-stage ACL rehabilitation protocols exist. Consequently, little is known about the tolerance for, and outcomes from, short-term exercise therapy programs in the early stage after injury. METHODS One-hundred patients were included in a 5-week progressive exercise therapy program, within 3 months after injury. Knee function before and after completion of the program was evaluated from isokinetic quadriceps and hamstrings muscle strength tests, 4 single-leg hop tests, 2 different self-assessment questionnaires, and a global rating of knee function. A 2-way mixed-model analysis of variance was conducted to evaluate changes from pretest to posttest for the limb symmetry index for muscle strength and single-leg hop tests, and the change in scores for the patient-reported questionnaires. In addition, absolute values and the standardized response mean for muscle strength and single-leg hop tests were calculated at pretest and posttest for the injured and uninjured limb. Adverse events during the 5-week period were recorded. RESULTS The progressive 5-week exercise therapy program led to significant improvements (P<.05) in knee function from pretest to posttest both for patients classified as potential copers and noncopers. Standardized response mean values for changes in muscle strength and single-leg hop performance from pretest to posttest for the injured limb were moderate to strong (0.49-0.84), indicating the observed improvements to be clinically relevant. Adverse events occurred in 3.9% of the patients. CONCLUSION Short-term progressive exercise therapy programs are well tolerated and should be incorporated in early-stage ACL rehabilitation, either to improve knee function before ACL reconstruction or as a first step in further nonoperative management. LEVEL OF EVIDENCE Therapy, level 2b.

Single-Legged Hop Tests as Predictors of Self-Reported Knee Function in Nonoperatively Treated Individuals With Anterior Cruciate Ligament Injury

Background: Previous studies have found significant predictors for functional outcome after anterior cruciate ligament (ACL) reconstruction; however, studies examining predictors for functional outcome in nonoperatively treated individuals are lacking. Hypothesis: Single-legged hop tests predict self-reported knee function (International Knee Documentation Committee [IKDC] 2000) in nonoperatively treated ACL-injured individuals 1 year after baseline testing. Study Design: Cohort study (prognosis); Level of evidence, 2. Methods: Ninety-one nonoperatively treated patients with an ACL injury were tested using 4 single-legged hop tests on average 74 ± 30 days after injury in a prospective cohort study. Eighty-one patients (89%) completed the IKDC 2000 1 year later. Patients with an IKDC 2000 score equal to or higher than the age- and gender-specific 15th percentile score from previously published data on an uninjured population were classified as having self-reported function within normal ranges. Logistic regression analyses were performed to identify predictors of self-reported knee function. The area under the curve (AUC) from receiver operating characteristic curves was used as a measure of discriminative accuracy. Optimal limb symmetry index (LSI) cutoff for the best single-legged hop test was defined as the LSI with the highest product of sensitivity and specificity. Results: Single hop for distance symmetry indexes predicted self-reported knee function at the 1-year follow-up (P = .036). Combinations of any 2 hop tests (AUC = 0.64-0.71) did not give a higher discriminative accuracy than the single hop alone (AUC = 0.71). A cutoff of 88% (LSI) for the single hop revealed a sensitivity of 71.4% and a specificity of 71.7%. Conclusion: The single hop for distance (LSI) significantly predicted self-reported knee function after 1 year in nonoperatively treated ACL-injured patients. Combinations of 2 single-legged hop tests did not lead to higher discriminative accuracy than the single hop alone.

Knee extensor muscle weakness is a risk factor for development of knee osteoarthritis. A systematic review and meta-analysis

The objective of this study was to perform a systematic review and meta-analysis on the association between knee extensor muscle weakness and the risk of developing knee osteoarthritis. A systematic review and meta-analysis was conducted with literature searches in Medline, SPORTDiscus, EMBASE, CINAHL, and AMED. Eligible studies had to include participants with no radiographic or symptomatic knee osteoarthritis at baseline; have a follow-up time of a minimum of 2 years, and include a measure of knee extensor muscle strength. Hierarchies for extracting data on knee osteoarthritis and knee extensor muscle strength were defined prior to data extraction. Meta-analysis was applied on the basis of the odds ratios (ORs) of developing symptomatic knee osteoarthritis or radiographic knee osteoarthritis in subjects with knee extensor muscle weakness. ORs for knee osteoarthritis and 95% confidence intervals (CI) were estimated and combined using a random effects model. Twelve studies were eligible for inclusion in the meta-analysis after the initial searches. Five cohort studies with a follow-up time between 2.5 and 14 years, and a total number of 5707 participants (3553 males and 2154 females), were finally included. The meta-analysis showed an overall increased risk of developing symptomatic knee osteoarthritis in participants with knee extensor muscle weakness (OR 1.65 95% CI 1.23, 2.21; I(2) = 50.5%). This systematic review and meta-analysis showed that knee extensor muscle weakness was associated with an increased risk of developing knee osteoarthritis in both men and women.

Consensus criteria for defining ‘successful outcome’ after ACL injury and reconstruction: a Delaware-Oslo ACL cohort investigation

Background No gold standard exists for identifying successful outcomes 1 and 2 years after operative and non-operative management of anterior cruciate ligament (ACL) injury. This limits the ability of a researcher and clinicians to compare and contrast the results of interventions. Purpose To establish a consensus based on expert consensus of measures that define successful outcomes 1 and 2 years after ACL injury or reconstruction. Methods Members of international sports medicine associations, including the American Orthopaedic Society for Sports Medicine, the European Society for Sports Traumatology, Surgery, and Knee Arthroscopy and the American Physical Therapy Association, were sent a survey via email. Blinded responses were analysed for trends with frequency counts. A summed importance percentage (SIP) was calculated and 80% SIP operationally indicated consensus. Results 1779 responses were obtained. Consensus was achieved for six measures in operative and non-operative management: the absence of giving way, patient return to sports, quadriceps and hamstrings’ strength greater than 90% of the uninvolved limb, the patient having not more than a mild knee joint effusion and using patient-reported outcomes (PRO). No single PRO achieved consensus, but threshold scores between 85 and 90 were established for PROs concerning patient performance. Conclusions The consensus identified six measures important for successful outcome after ACL injury or reconstruction. These represent all levels of the International Classification of Functioning: effusion, giving way, muscle strength (body structure and function), PRO (activity and participation) and return to sport (participation), and should be included to allow for comparison between interventions.

Nonsurgical or Surgical Treatment of ACL Injuries: Knee Function, Sports Participation, and Knee Reinjury The Delaware-Oslo ACL Cohort Study

BACKGROUND While there are many opinions about the expected knee function, sports participation, and risk of knee reinjury following nonsurgical treatment of injuries of the anterior cruciate ligament (ACL), there is a lack of knowledge about the clinical course following nonsurgical treatment compared with that after surgical treatment. METHODS This prospective cohort study included 143 patients with an ACL injury. Isokinetic knee extension and flexion strength and patient-reported knee function as recorded on the International Knee Documentation Committee (IKDC) 2000 form were collected at baseline, six weeks, and two years. Sports participation was reported monthly for two years with use of an online activity survey. Knee reinjuries were reported at the follow-up evaluations and in a monthly online survey. Repeated analysis of variance (ANOVA), generalized estimating equation (GEE) models, and Cox regression analysis were used to analyze group differences in functional outcomes, sports participation, and knee reinjuries, respectively. RESULTS The surgically treated patients (n = 100) were significantly younger, more likely to participate in level-I sports, and less likely to participate in level-II sports prior to injury than the nonsurgically treated patients (n = 43). There were no significant group-by-time effects on functional outcome. The crude analysis showed that surgically treated patients were more likely to sustain a knee reinjury and to participate in level-I sports in the second year of the follow-up period. After propensity score adjustment, these differences were nonsignificant; however, the nonsurgically treated patients were significantly more likely to participate in level-II sports during the first year of the follow-up period and in level-III sports over the two years. After two years, 30% of all patients had an extensor strength deficit, 31% had a flexor strength deficit, 20% had patient-reported knee function below the normal range, and 20% had experienced knee reinjury. CONCLUSIONS There were few differences between the clinical courses following nonsurgical and surgical treatment of ACL injury in this prospective cohort study. Regardless of treatment course, a considerable number of patients did not fully recover following the ACL injury, and future work should focus on improving the outcomes for these patients. LEVEL OF EVIDENCE Therapeutic Level II. See Instructions for Authors for a complete description of levels of evidence.

A Pair-Matched Comparison of Return to Pivoting Sports at 1 Year in Anterior Cruciate Ligament–Injured Patients After a Nonoperative Versus an Operative Treatment Course

Background: Patients usually return to pivoting sports between 6 months and 1 year after anterior cruciate ligament (ACL) reconstruction, but no matched study has so far examined 1-year return to sport rates in nonoperatively and operatively treated ACL-injured patients. Hypothesis: Anterior cruciate ligament-injured patients following a nonoperative treatment course, including recommendation of activity modification, will have lower return to pivoting sport rates than operatively treated patients 1 year after baseline testing/surgery, when matched by preinjury sports activity, age, and sex. Study Design: Cohort study; level of evidence, 3. Methods: Sixty-nine nonoperatively treated ACL-injured patients were pair-matched with 69 operatively treated patients (n = 138), based on specific preinjury sport, age, and sex. Nonoperatively treated patients were recommended not to return to level I sports. Patients were defined as nonoperatively or operatively treated according to their status at follow-up. The baseline and follow-up testing included registration of sports participation, KT-1000 arthrometer measurements, 4 hop tests, and patient-reported outcome measures. McNemars test and paired t tests or Wilcoxon test were used to compare outcomes of nonoperatively and operatively treated patients. Results: No significant baseline differences were found. At 12.9 ± 1.2 months (mean ± standard deviation) after baseline testing (nonoperative) and 12.7 ± 1.2 months after surgery (operative), there was no significant difference in overall return to sport rates (nonoperative: 68.1%, operative: 68.1%, P = 1.00), or in return to level I sport rates (nonoperative: 54.8%, operative: 61.9%, P = .66). Nonoperatively treated patients who participated in level I sports before injury had a significantly lower return to sport rate (54.8%) than nonoperatively treated patients who participated in level II sports (88.9%, P = .003). The nonoperatively treated patients had significantly higher knee joint laxity, but significantly better hop test limb symmetry indexes, Knee Outcome Survey Activities of Daily Living scores, and International Knee Documentation Committee Subjective Knee Form 2000 scores. None of the functional differences was larger than the smallest detectable difference. Conclusion: Anterior cruciate ligament-injured patients following a nonoperative treatment course, including recommendations of activity modifications, and operatively treated patients did not have significantly different rates of returning to pivoting sports after 1 year in this pair-matched cohort study. Clinicians should be aware of a potentially high level of noncompliance to recommendations of activity modifications. Although these results show that it is possible for nonoperatively treated patients to return to sport after rehabilitation, future follow-ups are needed to examine whether these patients maintain sports participation over time, and what long-term consequences they may suffer regarding subsequent injuries and knee osteoarthritis.

Anterior Cruciate Ligament—Deficient Potential Copers and Noncopers Reveal Different Isokinetic Quadriceps Strength Profiles in the Early Stage After Injury

Background Isokinetic muscle strength testing using the peak torque value is the most frequently included quadriceps muscle strength measurement for anterior cruciate ligament (ACL)—injured subjects. Purpose and Hypotheses The purpose of this study was to investigate quadriceps muscle performance during the whole isokinetic curve in subjects with ACL deficiency classified as potential copers or noncopers and to investigate whether these curve profiles were associated with single-legged hop performance. We hypothesized that quadriceps muscle torque at other knee flexion angles than peak torque would give more information about quadriceps muscle strength deficits. Furthermore, we hypothesized that there would be significant torque differences between potential copers and noncopers and a significant relationship between angle-specific torque values and single-legged hop performance. Study Design Cross-sectional study; Level of evidence, 3. Methods Seventy-six individuals with a complete unilateral ACL rupture within the last 3 months were included. The subjects were classified as potential copers and noncopers. Isokinetic quadriceps muscle tests were performed at 60 deg/s. Mean torque values were calculated for peak torque as well as for specific knee flexion angles. The 1-legged hop and the 6-m timed hop tests were included, and symmetry indices were used. Results The peak torque value did not identify the largest quadriceps muscle strength deficit. Rather, these were established at knee flexion angles of less than 40°. There were significant differences in angle-specific torque values between potential copers and noncopers (P < .05). Moderate to strong associations were disclosed between angle-specific torque values and single-legged hop performance, but only for noncopers (r ≥ .32-.58). Conclusion Angle-specific quadriceps muscle torque values of less than 40° of knee flexion provide more information on the quadriceps strength deficits after ACL injury than the commonly used peak torque values. Interpretation of the isokinetic curve profiles seems to be of clinical importance for the evaluation of quadriceps muscle performance after ACL injury.

How does a combined preoperative and postoperative rehabilitation programme influence the outcome of ACL reconstruction 2 years after surgery? A comparison between patients in the Delaware-Oslo ACL Cohort and the Norwegian National Knee Ligament Registry

Background Preoperative knee function is associated with successful postoperative outcome after anterior cruciate ligament reconstruction (ACLR). However, there are few longer term studies of patients who underwent progressive preoperative and postoperative rehabilitation compared to usual care. Objectives To compare preoperative and 2 year postoperative patient-reported outcomes (PROs) in patients undergoing progressive preoperative and postoperative rehabilitation at a sports medicine clinic compared with usual care. Methods We included patients aged 16–40 years undergoing primary unilateral ACLR. The preoperative and 2 year postoperative Knee Injury and Osteoarthritis Outcome Score (KOOS) of 84 patients undergoing progressive preoperative and postoperative rehabilitation at a sports medicine clinic (Norwegian Research Center for Active Rehabilitation (NAR) cohort) were compared with the scores of 2690 patients from the Norwegian National Knee Ligament Registry (NKLR). The analyses were adjusted for sex, age, months from injury to surgery and cartilage/meniscus injury at ACLR. Results The NAR cohort had significantly better preoperative KOOS in all subscales, with clinically relevant differences (>10 points) observed in KOOS Pain, activities of daily living (ADL), Sports and Quality of Life. At 2 years, the NAR cohort still had significantly better KOOS with clinically relevant differences in KOOS Symptoms, Sports and Quality of Life. At 2 years, 85.7–94% of the patients in the NAR cohort scored within the normative range of the different KOOS subscales, compared to 51.4–75.8% of the patients in the NKLR. Conclusions Patients in a prospective cohort who underwent progressive preoperative and postoperative rehabilitation at a sports medicine clinic showed superior patient-reported outcomes both preoperatively and 2 years postoperatively compared to patients in the NKLR who received usual care.