James R. Slauterbeck

Understanding and Preventing Noncontact Anterior Cruciate Ligament Injuries A Review of the Hunt Valley II Meeting, January 2005

The incidence of noncontact anterior cruciate ligament injuries in young to middle-aged athletes remains high. Despite early diagnosis and appropriate operative and nonoperative treatments, posttraumatic degenerative arthritis may develop. In a meeting in Atlanta, Georgia (January 2005), sponsored by the American Orthopaedic Society for Sports Medicine, a group of physicians, physical therapists, athletic trainers, biomechanists, epidemiologists, and other scientists interested in this area of research met to review current knowledge on risk factors associated with noncontact anterior cruciate ligament injuries, anterior cruciate ligament injury biomechanics, and existing anterior cruciate ligament prevention programs. This article reports on the presentations, discussions, and recommendations of this group.

Mechanisms of Anterior Cruciate Ligament Injury in Basketball Video Analysis of 39 Cases

Background The mechanisms of anterior cruciate ligament injury in basketball are not well defined. Purpose To describe the mechanisms of anterior cruciate ligament injury in basketball based on videos of injury situations. Study Design Case series; Level of evidence, 4. Methods Six international experts performed visual inspection analyses of 39 videos (17 male and 22 female players) of anterior cruciate ligament injury situations from high school, college, and professional basketball games. Two predefined time points were analyzed: initial ground contact and 50 milliseconds later. The analysts were asked to assess the playing situation, player behavior, and joint kinematics. Results There was contact at the assumed time of injury in 11 of the 39 cases (5 male and 6 female players). Four of these cases were direct blows to the knee, all in men. Eleven of the 22 female cases were collisions, or the player was pushed by an opponent before the time of injury. The estimated time of injury, based on the group median, ranged from 17 to 50 milliseconds after initial ground contact. The mean knee flexion angle was higher in female than in male players, both at initial contact (15° vs 9°, P = .034) and at 50 milliseconds later (27° vs 19°, P = .042). Valgus knee collapse occurred more frequently in female players than in male players (relative risk, 5.3; P = .002). Conclusion Female players landed with significantly more knee and hip flexion and had a 5.3 times higher relative risk of sustaining a valgus collapse than did male players. Movement patterns were frequently perturbed by opponents. Clinical Relevance Preventive programs to enhance knee control should focus on avoiding valgus motion and include distractions resembling those seen in match situations.

An analysis of the quality of cartilage repair studies.

BACKGROUND Most lesions of articular cartilage do not heal spontaneously and may lead to secondary osteoarthritis. It is not known whether the optimistic reports on the short and long-term results of several different cartilage repair techniques are based on sound methodological quality. METHODS We performed a literature search in MEDLINE, CINAHL, the Cochrane Central Register, and EMBASE and included studies in which the primary aim of the investigation was to report the outcome after cartilage repair in the knee with use of microfracture, autologous osteochondral transplantation, autologous periosteal transplantation, or autologous chondrocyte implantation. We scored the quality of the studies using a modified Coleman Methodology Score with ten criteria, which results in a final score between 0 and 100. Studies were also assessed with use of the level-of-evidence rating used in the American Volume of The Journal of Bone and Joint Surgery. We collected data on the year of publication, the reported postoperative results, and the outcome measures used to assess the results. RESULTS Sixty-one studies involving a total of 3987 surgical procedures were included. The average methodology score was 43.5 of 100. Methodological deficiencies were found with respect to five criteria: the type of study, description of the rehabilitation protocol, outcome criteria, outcome assessment, and subject selection process. Large variations in the reported outcome were seen within each treatment modality, and no significant differences were found between each kind of therapy (p = 0.11). The methodology score correlated positively with the level-of-evidence rating (r = 0.668, p < 0.0001), but there were large variations in the methodology score within each level. The linear regression analysis weighted by the number of patients demonstrated a negative yet not significant correlation between the methodology score and the results reported in nineteen studies with use of the Lysholm Scale (r = -0.29, p = 0.19). A total of twenty-seven different clinical outcome measurement scales were used to assess outcome. CONCLUSIONS The generally low methodological quality found in the studies included in this analysis indicates that caution is required when interpreting results after surgical cartilage repair. Firm recommendations on which procedure to choose cannot be given at this time on the basis of these studies. More attention should be paid to methodological quality when designing, performing, and reporting clinical studies. LEVEL OF EVIDENCE Therapeutic Level III.

Shallow Medial Tibial Plateau and Steep Medial and Lateral Tibial Slopes: New Risk Factors for Anterior Cruciate Ligament Injuries

Background The geometry of the tibial plateau has been largely ignored as a source of possible risk factors for anterior cruciate ligament injury. Discovering the anterior cruciate ligament injury risk factors associated with the tibial plateau may lead to delineation of the existing sex-based disparity in anterior cruciate ligament injuries and help develop strategies for the prevention of anterior cruciate ligament injuries regardless of gender. Hypothesis Individuals with a shallower medial tibial depth of concavity, while having increased posteriorly directed slope of their tibial plateau, are at increased risk of suffering an anterior cruciate ligament injury compared with those with decreased posterior slope and increased medial tibial depth. Furthermore, these relationships are different between men and women. Study Design Case-control study (prevalence); Level of evidence, 3. Methods The medial, lateral, and coronal tibial plateau slopes as well as the medial tibial depth of concavity in 55 uninjured controls (33 women and 22 men) and 49 anterior cruciate ligament—injured cases (27 women and 22 men) were measured using magnetic resonance images. First, a preliminary t test was performed to establish any existing differences between groups. Next, a logistic regression model was developed to determine the probability of anterior cruciate ligament injury in an individual based on the measured covariates. Results The female anterior cruciate ligament—injured cases had increased lateral tibial slope (P = .03) and shallower medial tibial depth (P = .0003) compared with the uninjured controls, while male cases had increased lateral and medial tibial slope (P = .02) and shallower medial tibial depth (P = .0004) compared with controls. The logistic regression analysis and odds ratio estimates showed that medial tibial depth is an important risk factor (odds ratio = 3.03 per 1 mm decrease in its value), followed by lateral tibial slope (odds ratio = 1.17 per 1° increase in its value) in all participants. The medial tibial slope (odds ratio = 1.18 per 1° increase in its value) was a risk factor only in men. Conclusion A combination of increased posterior-directed tibial plateau slope and shallow medial tibial plateau depth could be a major risk factor in anterior cruciate ligament injury susceptibility regardless of gender. Different injury risk models may be needed for men and women as other key risk factors are identified.

The Geometry of the Tibial Plateau and Its Influence on the Biomechanics of the Tibiofemoral Joint

BACKGROUND The geometry of the tibial plateau is complex and asymmetric. Previous research has characterized subject-to-subject differences in the tibial plateau geometry in the sagittal plane on the basis of a single parameter, the posterior slope. We hypothesized that (1) there are large subject-to-subject variations in terms of slopes, the depth of concavity of the medial plateau, and the extent of convexity of the lateral plateau; (2) medial tibial slope and lateral tibial slope are different within subjects; (3) there are sex-based differences in the slopes as well as concavities and convexities of the tibial plateau; and (4) age is not associated with any of the measured parameters. METHODS The medial, lateral, and coronal slopes and the depth of the osseous portion of the tibial plateau were measured with use of sagittal and coronal magnetic resonance images that were made for thirty-three female and twenty-two male subjects, and differences between the sexes with respect to these four parameters were assessed. Within-subject differences between the medial and lateral tibial slopes also were assessed. Correlation tests were performed to examine the existence of a linear relationship between various slopes as well as between slopes and subject age. RESULTS The range of subject-to-subject variations in the tibial slopes was substantive for males and females. However, the mean medial and lateral tibial slopes in female subjects were greater than those in male subjects (p < 0.05). In contrast, the mean coronal tibial slope in female subjects was less than that in male subjects (p < 0.05). The correlation between medial and lateral tibial slopes was poor. The within-subject difference between medial and lateral tibial slopes was significant (p < 0.05). No difference in medial tibial plateau depth was found between the sexes. The subchondral bone on the lateral part of the tibia, within the articulation region, was mostly flat. Age was not associated with the observed results. CONCLUSIONS The geometry of the osseous portion of the tibial plateau is more robustly explained by three slopes and the depth of the medial tibial condyle.

Sex-Based Differences in the Anthropometric Characteristics of the Anterior Cruciate Ligament and Its Relation to Intercondylar Notch Geometry A Cadaveric Study

Background A significantly higher rate of anterior cruciate ligament injuries occurs in women involved in sports activities compared to the corresponding male population. Reasons for this disparity are not well understood; however, sex-based differences in the geometry of the anterior cruciate ligament, its morphologic characteristics, and the intercondylar notch size have been cited as possible factors. Hypotheses (1) The anterior cruciate ligament in women has a shorter length, and smaller cross-sectional area and volume than that in men. (2) The female anterior cruciate ligament has a lower mass density. (3) Ligament size is proportional to notch width in both male and female populations. Study Design Descriptive laboratory study. Methods Using a 3-dimensional imaging system, the authors measured the geometric parameters, including length, area, and volume, of the anterior cruciate ligaments of 10 male and 10 female donors (all Caucasian). A digital image of the frontal plane of the knee flexed at 90° was used to measure notch size. After the ligaments removal from its attachment sites, its mass was measured using a digital balance. Geometric parameters, mass density, and notch size were compared based on sex. Correlation analyses between ligament size and body anthropometric characteristics, and between notch size and ligament size were performed. Results The anterior cruciate ligament in women was smaller in length, cross-sectional area, volume, and mass when compared to that in men. No significant difference in ligament mass density was found between the sexes. Also, no differences were found in notch geometry between male and female populations. A correlation between notch size and ligament size was found for men but not for women. Conclusions Because the densities of female and male anterior cruciate ligaments appear to be similar, the smaller ligament size in women may contribute to their having a higher rate of ligament injuries. Anterior cruciate ligament size increases in proportion to notch width in men but not in women.

A Prospective Evaluation of the Landing Error Scoring System (LESS) as a Screening Tool for Anterior Cruciate Ligament Injury Risk

Background: Anterior cruciate ligament (ACL) injuries are immediately disabling, costly, take a significant amount of time to rehabilitate, and are associated with an increased risk of developing posttraumatic osteoarthritis of the knee. Specific multiplanar movement patterns of the lower extremity, such as those associated with the drop vertical jump (DVJ) test, have been shown to be associated with an increased risk of suffering noncontact ACL injuries. The Landing Error Scoring System (LESS) has been developed as a tool that can be applied to identify individuals who display at-risk movement patterns during the DVJ. Hypothesis: An increase in LESS score is associated with an increased risk of noncontact ACL injury. Study Design: Case-control study; Level of evidence, 3. Methods: Over a 3-year interval, 5047 high school and college participants performed preseason DVJ tests that were recorded using commercial video cameras. All participants were followed for ACL injury during their sports season, and video data from injured participants and matched controls were then assessed with the LESS. Conditional logistic regression analysis was used to examine the association between LESS score and ACL injury risk in all participants as well as subgroups of female, male, high school, and college participants. Results: There was no relationship between the risk of suffering ACL injury and LESS score whether measured as a continuous or a categorical variable. This was the case for all participants combined (odds ratio, 1.04 per unit increase in LESS score; 95% confidence interval, 0.80-1.35) as well as within each subgroup (odds ratio range, 0.99-1.14). Conclusion: The LESS did not predict ACL injury in our cohort of high school and college athletes.

A Biomechanical Study of Replacement of the Posterior Cruciate Ligament with a Graft. Part I: Isometry, Pre-Tension of the Graft, and Anterior-Posterior Laxity*

Twelve fresh-frozen knee specimens from cadavera were subjected to anterior-posterior laxity testing with 200 newtons of force applied to the tibia; testing was performed before and after a femoral load-cell was connected to a mechanically isolated cylindrical cap of subchondral femoral bone containing the femoral origin of the posterior cruciate ligament. The posterior cruciate ligament then was removed, the proximal end of a thin trial isometer wire was attached to one of four points designated on the femur, and displacement of the distal end of the wire relative to the tibia was measured over a 120-degree range of motion. The potted end of a ten-millimeter-wide bone-patellar ligament-bone graft was centered over the femoral origin of the ligament and attached to the femoral load-cell. Isometry measurements were repeated with the wire attached to the bone block of the free end of the graft in the tibial tunnel. Force was recorded at the load-cell (representing force in the intra-articular portion of the graft) as pre-tension was applied, with use of a calibrated spring-scale, to the tibial end of the graft. A laxity-matched pre-tension of the graft was determined such that the anterior-posterior laxity of the reconstructed knee at 90 degrees of flexion was within one millimeter of the laxity that was measured after installation of the load-cell. Anterior-posterior testing was repeated after insertion of the graft at the laxity-matched pre-tension. The least amount of change in the relative displacement of the trial wire over the 120-degree range of flexion occurred when the wire was attached to the proximal point on the femur (a point on the proximal margin of the femoral origin of the posterior cruciate ligament, midway between the anterior and posterior borders of the ligament). The greatest change in the relative displacement was associated with the anterior point (a point on the anterior margin of the femoral origin of the ligament, midway between the proximal and distal borders). The mean relative displacements of the trial wire when it was attached to a point at the center of the femoral origin of the ligament were not significantly different from the corresponding mean displacements of the distal end of the graft when the proximal end of the graft was centered at this point. At 90 degrees of flexion, the force recorded by the load-cell averaged 64 to 74 per cent of the force applied to the tibial end of the graft. The laxity-matched pre-tension of the graft at 90 degrees of flexion (as recorded by the load-cell) ranged from six to 100 newtons (mean and standard deviation, 43.0 ± 33.4 newtons). With the numbers available, the mean laxities after insertion of the graft were not significantly different, at any angle of flexion, from the corresponding mean values after installation of the load-cell. CLINICAL RELEVANCE: Isometer readings from a trial wire attached to a point on the femur provided an accurate indication of the change in the length of a graft subsequently centered at that point. Anteriorly placed femoral tunnels should be avoided, as the isometer readings indicated increased tension, with flexion of the knee, in a graft placed in this region. The force in the intra-articular portion of the graft was always less than the force applied to the bone block in the tibial tunnel. Therefore, the femoral end of the graft should be tensioned to avoid frictional losses from the severe bend in the graft as it passes over the posterior tibial plateau. With correct pre-tensioning of a graft, normal anterior-posterior laxity at 0 to 90 degrees of flexion can be restored. However, because of the considerable range in the laxity-matched pre-tensions, we recommend that the pre-tension be greater than forty-three newtons for all patients to ensure that normal laxity is restored.

Preparticipation physical examination using a box drop vertical jump test in young athletes: the effects of puberty and sex.

ObjectiveNeuromuscular performance increases rapidly in males throughout pubertal development, whereas no similar neuromuscular spurt occurs in females. This fact may underlie neuromuscular imbalances related to increased risk of injury in females. The hypothesis: female athletes would demonstrate mismatched landing force to power production compared with males. DesignThis study used a cross-sectional study design to compare cohorts of pubertal stage-matched males and females during preparticipation physical examination. SettingAn onsite preparticipation physical examination at a Texas High School. ParticipantsTwo hundred seventy-five middle school and high school athletes (Tanner Stages 2 to 5) volunteered to participate (87 females, 188 males) in a preseason physical screening. Main Outcome MeasuresVertical ground reaction forces were used to determine the effects of sex and pubertal stage on the calculated measures. Subjects performed 3 drop vertical jumps onto a portable force platform. ResultsFemales demonstrated no increase in vertical jump height whereas males increased on average 12.5% between pubertal stages (P=0.002). The ratios of the drop landing force to drop take-off and maximum landing force to maximum take-off force were decreased in males as they matured (P<0.05) whereas females did not change between pubertal stages. ConclusionsPreparticipation physical examination may be used to determine potential high-risk landing force profiles in young athletes before participation. Female athletes may exhibit high-risk landing profiles at all stages of pubertal development that may increase risk of injury during landing compared with males. Clinical RelevancePreseason intervention may be warranted for females with high-risk landing profiles identified during preparticipation physical examination.

Risk Factors for Anterior Cruciate Ligament Injury: A Review of the Literature — Part 1: Neuromuscular and Anatomic Risk

Context: Injuries to the anterior cruciate ligament (ACL) of the knee are immediately debilitating and can cause long-term consequences, including the early onset of osteoarthritis. It is important to have a comprehensive understanding of all possible risk factors for ACL injury to identify individuals who are at risk for future injuries and to provide an appropriate level of counseling and programs for prevention. Objective: This review, part 1 of a 2-part series, highlights what is known and still unknown regarding anatomic and neuromuscular risk factors for injury to the ACL from the current peer-reviewed literature. Data Sources: Studies were identified from MEDLINE (1951–March 2011) using the MeSH terms anterior cruciate ligament, knee injury, and risk factors. The bibliographies of relevant articles and reviews were cross-referenced to complete the search. Study Selection: Prognostic studies that utilized the case-control and prospective cohort study designs to evaluate risk factors for ACL injury were included in this review. Results: A total of 50 case-control and prospective cohort articles were included in the review, and 30 of these studies focused on neuromuscular and anatomic risk factors. Conclusions: Several anatomic and neuromuscular risk factors are associated with increased risk of suffering ACL injury—such as female sex and specific measures of bony geometry of the knee joint, including decreased intercondylar femoral notch size, decreased depth of concavity of the medial tibial plateau, increased slope of the tibial plateaus, and increased anterior-posterior knee laxity. These risk factors most likely act in combination to influence the risk of ACL injury; however, multivariate risk models that consider all the aforementioned risk factors in combination have not been established to explore this interaction.