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Articles by L Engebretsen
Total Records ( 9 ) for L Engebretsen
  J. M Alonso , P. M Tscholl , L Engebretsen , M Mountjoy , J Dvorak and A. Junge

To analyse the frequency and characteristics of sports injuries and illnesses incurred during the World Athletics Championships.


Prospective recording of newly occurred injuries and illnesses.


Twelfth International Association of Athletics Federations World Championships in Athletics 2009 in Berlin, Germany.


National team physicians and physiotherapists and 1979 accredited athletes; Local Organising Committee physicians working in the Medical Centres.

Main outcome measures

Incidence and characteristics of newly incurred injuries and illnesses.


236 injury incidents with 262 injured body parts and 269 different injury types were reported, representing an incidence of 135.4 injuries per 1000 registered athletes. Eighty percent affected the lower extremity. Thigh strain (13.8%) was the main diagnosis. Overuse (44.1%) was the predominant cause. Most injuries were incurred during competition (85.9%). About 43.8% of all injury events were expected to result in time-loss. 135 illnesses were reported, signifying an incidence of 68.2 per 1000 registered athletes. Upper respiratory tract infection was the most common condition (30.4%) and infection was the most frequent cause (32.6%). The incidence of injury and illnesses varied substantially among the events.


The risk of injury varied with each discipline. Preventive measures should be specific and focused on minimising the potential for overuse. Attention should be paid to ensure adequate rehabilitation of previous injuries. The addition of the illness part to the injury surveillance system proved to be feasible. As most illnesses were caused by infection of the respiratory tract or were environmentally related, preventive interventions should focus on decreasing the risk of transmission, appropriate event scheduling and heat acclimatisation.

  B. E Oiestad , L Engebretsen , K Storheim and M. A. Risberg

This is a systematic review of studies on the prevalence of osteoarthritis in the tibiofemoral joint more than 10 years after an anterior cruciate ligament injury, the radiologic classification methods used, and risk factors for development of knee osteoarthritis.


A systematic search was performed in PubMed, EMBASE, and AMED. Inclusion criteria were studies involving patients with anterior cruciate ligament injury, either isolated or combined with medial collateral ligament or meniscal injury and either surgically or nonsurgically treated, and a minimum 10-year follow-up with radiologic assessment. Methodological quality was evaluated using a modified version of the Coleman methodology score.


Seven prospective and 24 retrospective studies were included. The mean modified Coleman methodology score was 52 of 90. Reported prevalence of knee osteoarthritis for subjects with isolated anterior cruciate ligament injury was between 0% and 13%. For subjects with anterior cruciate ligament and additional meniscal injury, the prevalence varied between 21% and 48%. Seven different radiologic classification systems were used in the studies. Only 3 studies reported reliability results for the radiologic assessments. The most frequently reported risk factor for development of knee osteoarthritis was meniscal injury.


This systematic review suggests that the prevalence rates of knee osteoarthritis after anterior cruciate ligament reconstruction reported by previous reviews have been too high. The highest rated studies reported low prevalence of knee osteoarthritis for individuals with isolated anterior cruciate ligament injury (0%–13%) and a higher prevalence of knee osteoarthritis for subjects with combined injuries (21%–48%). Overall, the modified Coleman methodology score was low for the included studies. No universal methodological radiologic classification method exists, making comparisons of the studies and stating firm conclusions on the prevalence of knee osteoarthritis more than 10 years after anterior cruciate ligament injury difficult.

  A Junge , L Engebretsen , M. L Mountjoy , J. M Alonso , P. A. F. H Renstrom , M. J Aubry and J. Dvorak

Standardized assessment of sports injuries provides important epidemiological information and also directions for injury prevention.


To analyze the frequency, characteristics, and causes of injuries incurred during the Summer Olympic Games 2008.

Study Design

Descriptive epidemiology study.


The chief physicians and/or chief medical officers of the national teams were asked to report daily all injuries newly incurred during the Olympic Games on a standardized injury report form. In addition, injuries were reported daily by the physicians at the medical stations at the different Olympic venues and at the polyclinic in the Olympic Village.


Physicians and/or therapists of 92 national teams covering 88% of the 10 977 registered athletes took part in the study. In total, 1055 injuries were reported, resulting in an incidence of 96.1 injuries per 1000 registered athletes. Half of the injuries (49.6%) were expected to prevent the athlete from participating in competition or training. The most prevalent diagnoses were ankle sprains and thigh strains. The majority (72.5%) of injuries were incurred in competition. One third of the injuries were caused by contact with another athlete, followed by overuse (22%) and noncontact incidences (20%). Injuries were reported from all sports, but their incidence and characteristics varied substantially. In relation to the number of registered athletes, the risk of incurring an injury was highest in soccer, taekwondo, hockey, handball, weightlifting, and boxing (all ≥15% of the athletes) and lowest for sailing, canoeing/kayaking, rowing, synchronized swimming, diving, fencing, and swimming.


The data indicate that the injury surveillance system covered almost all of the participating athletes, and the results highlight areas of high risk for sport injury such as the in-competition period, the ankle and thigh, and specific sports. The identification of these factors should stimulate future research and subsequent policy change to prevent injury in elite athletes.

  C. J Anderson , B. D Westerhaus , S. D Pietrini , C. G Ziegler , C. A Wijdicks , S Johansen , L Engebretsen and R. F. LaPrade

Background: Currently in double-bundle anterior cruciate ligament (ACL) reconstructions, the range of knee flexion angles that surgeons use for anteromedial (AM) and posterolateral (PL) bundle graft fixation spans from 0° to 90° for both bundle grafts. Despite the recent popularity of this procedure, no consensus exists on an optimal set of AM and PL graft fixation angles.

Hypothesis: Graft fixation angles that simulate the native tensioning relationship of the AM and PL bundles will produce kinematic results similar to the intact knee, while graft fixation angles that do not simulate this relationship will under- or overconstrain the knee.

Study design: Controlled laboratory study.

Methods: Twelve cadaveric knees were biomechanically tested in the intact state, ACL-sectioned state, and a randomized order of 7 double-bundle ACL reconstructed states at multiple graft fixation angle combinations. For each test state, data were collected for 88 N anterior tibial loads, 10 N·m valgus torques, 5 N·m internal rotation torques, and 2 simulated pivot shift loads consisting of a 5 N·m internal rotation torque coupled with either a 10 N·m valgus torque or an 88 N anterior tibial load at 0°, 20°, 30°, 60°, and 90° of knee flexion.

Results: The AM and PL graft fixation angle combinations of 0°/0° (AM graft fixation angle/PL graft fixation angle), 60°/0°, 45°/15°, and 75°/15° restored normal laxity to the reconstructed knee in all of the biomechanical tests. The 30°/30°, 60°/60°, and 90°/90° graft fixation angle combinations significantly restricted knee laxity compared with the intact state in various biomechanical tests.

Conclusion: We found that as long as the PL bundle graft was fixed between 0° and 15°, the AM graft could be fixed up to 75° without restricting knee laxity. However, fixation of the PL graft at 30° of knee flexion and above significantly overconstrained the knee.

Clinical Relevance: This study provides a range of angles that can be used in double-bundle ACL reconstructions to restore normal knee stability without causing overconstraint.

  C. A Wijdicks , D. T Ewart , D. J Nuckley , S Johansen , L Engebretsen and R. F. LaPrade

Background: The structural properties of the individual components of the superficial medial collateral ligament (MCL), deep MCL, and posterior oblique ligament (POL) have not been studied in isolation. To define the necessary strength requirements for an anatomical medial knee reconstruction, knowledge of these structural properties is necessary.

Hypothesis: The components of the superficial MCL, POL, and deep MCL have significantly different structural properties.

Study Design: Controlled laboratory study.

Methods: This study used 20 fresh-frozen nonpaired cadaveric knee specimens with a mean age of 54 years (range, 27 to 68 years). These knees provided 8 samples for each tested medial knee structure, which was individually isolated and loaded to failure at 20 mm per minute. Specifically tested were the superficial MCL with intact femoral and detached proximal tibial attachments, the superficial MCL with intact femoral and detached distal tibial attachments, the central arm of the POL, and the isolated deep MCL. Load was recorded as a function of displacement. Stiffness of the ligament at failure was calculated from these measurements.

Results: The mean load at failure for the superficial MCL with the intact femoral and distal tibial attachments was 557 N. Mean load at failure was 88 N for the intact femoral and proximal tibial divisions of the superficial MCL, 256 N for the POL, and 101 N for the deep MCL. Stiffness of the ligaments just before failure was 63, 17, 38, and 27 N/mm, in the same order as above.

Conclusion: The proximal and distal tibial divisions of the superficial MCL, POL, and deep MCL produced loads of clinical importance.

Clinical Relevance: Knowledge of the structural properties of these attachment sites will assist in reconstruction graft choices, fixation method choices, and overall operative treatment of medial knee injury.

  M McCarthy , L Camarda , C. A Wijdicks , S Johansen , L Engebretsen and R. F. LaPrade

Background: No biomechanical study has been performed analyzing the merits of reconstructing the popliteofibular ligament (PFL) through a tibial tunnel with an anatomic reconstruction of the posterolateral knee.

Hypothesis: There is no difference in an anatomic posterolateral knee reconstruction with or without a PFL reconstruction placed through a tibial tunnel in restoring knee motion to the intact, uninjured state, and the knee is not overconstrained with this reconstruction.

Study Design: Controlled laboratory study.

Methods: Eight paired knees were tested in the intact state and then sectioned to simulate a grade III posterolateral knee injury. The reconstruction for the first paired knee reconstructed the PFL (through a tibial tunnel), popliteus tendon, and fibular collateral ligament (group 1); the matched knee reconstruction involved only the popliteus tendon and fibular collateral ligament (group 2).

Results: Reconstructions for group 1 knees restored knee motion to the intact state for all tested conditions at all knee flexion angles with no overconstraint of the knee. Without reconstructing the PFL (group 2), small but significant increases in motion were found for varus translation at 0° (3.0°), 20° (3.1°), and 60° (3.8°) of knee flexion compared with the intact state. At 60° and 90° of flexion, the reconstruction for group 2 had small but significant increases in internal rotation compared with the intact state (1.3° and 1.8°, respectively).

Conclusion: Inclusion of the PFL through a tibial tunnel as part of an anatomic posterolateral knee reconstruction restores knee stability back to the intact state and does not overconstrain the knee. Furthermore, inclusion of the PFL through a tibial tunnel restored normal internal rotation.

Clinical Relevance: The PFL should be included in anatomic reconstructions of grade III posterolateral knee injuries with placement through a tibial tunnel to best restore the intact, preinjury knee motion state and, most notably, normal internal rotation without evidence of overconstraint of the knee.

  A. H Engebretsen , G Myklebust , I Holme , L Engebretsen and R. Bahr

Background: This study was conducted to determine if risk factors for groin injuries among male soccer players could be identified.

Hypothesis: Previous groin injuries, reduced function scores, age, findings on clinical examination, and low isometric groin strength are associated with increased risk of new groin injuries.

Study Design: Cohort study; Level of evidence, 3.

Methods: A total of 508 players representing 31 amateur teams were tested during the 2004 preseason for potential risk factors for groin injury through a questionnaire on previous injury and function score (Groin Outcome Score [GrOS]) and a clinical examination of the groin. Generalized estimating equations were used in univariate analyses to identify candidate risk factors, and factors with a P value <.10 were then examined in a multivariate model.

Results: During the soccer season, 61 groin injuries affecting 55 legs (51 players) were registered. The total incidence of groin injuries was 0.6 injuries per 1000 playing hours (95% confidence interval [CI], 0.4-0.7), 0.3 injuries per 1000 training hours (95% CI, 0.2-0.4), and 1.8 injuries per 1000 match hours (95% CI, 1.2-2.5). In a multivariate analysis, previous acute groin injury (adjusted odds ratio [OR], 2.60; 95% CI, 1.10-6.11) and weak adductor muscles as determined clinically (adjusted OR, 4.28; 95% CI, 1.31-14.0) were significantly associated with increased risk of groin injuries. A multivariate analysis based only on acute time-loss injuries revealed the 40-m sprint test result (adjusted OR, 2.03 for 1 standard deviation change [injured group faster]; 95% CI, 1.06-3.88; P = .03) and functional testing of the rectal abdominal muscles (adjusted OR, 15.5 [painful in 19% of the players in the injured group compared to 16% in the uninjured group]; 95% CI, 1.11-217; P = .04) as significant risk factors.

Conclusion: A history of acute groin injury and weak adductor muscles are significant risk factors for new groin injuries.

  B. E Oiestad , I Holm , A. K Aune , R Gunderson , G Myklebust , L Engebretsen , M. A Fosdahl and M. A. Risberg

Background: Few prospective long-term studies of more than 10 years have reported changes in knee function and radiologic outcomes after anterior cruciate ligament (ACL) reconstruction.

Purpose: To examine changes in knee function from 6 months to 10 to 15 years after ACL reconstruction and to compare knee function outcomes over time for subjects with isolated ACL injury with those with combined ACL and meniscal injury and/or chondral lesion. Furthermore, the aim was to compare the prevalence of radiographic and symptomatic radiographic knee osteoarthritis between subjects with isolated ACL injuries and those with combined ACL and meniscal and/or chondral lesions 10 to 15 years after ACL reconstruction.

Study Design: Cohort study; Level of evidence, 2.

Methods: Follow-up evaluations were performed on 221 subjects at 6 months, 1 year, 2 years, and 10 to 15 years after ACL reconstruction with bone-patellar tendon-bone autograft. Outcome measurements were KT-1000 arthrometer, Lachman and pivot shift tests, Cincinnati knee score, isokinetic muscle strength tests, hop tests, visual analog scale for pain, Tegner activity scale, and the Kellgren and Lawrence classification.

Results: One hundred eighty-one subjects (82%) were evaluated at the 10- to 15-year follow-up. A significant improvement over time was revealed for all prospective outcomes of knee function. No significant differences in knee function over time were detected between the isolated and combined injury groups. Subjects with combined injury had significantly higher prevalence of radiographic knee osteoarthritis compared with those with isolated injury (80% and 62%, P = .008), but no significant group differences were shown for symptomatic radiographic knee osteoarthritis (46% and 32%, P = .053).

Conclusion: An overall improvement in knee function outcomes was detected from 6 months to 10 to 15 years after ACL reconstruction for both those with isolated and combined ACL injury, but significantly higher prevalence of radiographic knee osteoarthritis was found for those with combined injuries.

  H Koga , A Nakamae , Y Shima , J Iwasa , G Myklebust , L Engebretsen , R Bahr and T. Krosshaug

Background: The mechanism for noncontact anterior cruciate ligament injury is still a matter of controversy. Video analysis of injury tapes is the only method available to extract biomechanical information from actual anterior cruciate ligament injury cases.

Purpose: This article describes 3-dimensional knee joint kinematics in anterior cruciate ligament injury situations using a model-based image-matching technique.

Study Design: Case series; Level of evidence, 4.

Methods: Ten anterior cruciate ligament injury video sequences from women’s handball and basketball were analyzed using the model-based image-matching method.

Results: The mean knee flexion angle among the 10 cases was 23° (range, 11°-30°) at initial contact (IC) and had increased by 24° (95% confidence interval [CI], 19°-29°) within the following 40 milliseconds. The mean valgus angle was neutral (range, –2° to 3°) at IC, but had increased by 12° (95% CI, 10°-13°) 40 milliseconds later. The knee was externally rotated 5° (range, –5° to 12°) at IC, but rotated internally by 8° (95% CI, 2°-14°) during the first 40 milliseconds, followed by external rotation of 17° (95% CI, 13°-22°). The mean peak vertical ground-reaction force was 3.2 times body weight (95% CI, 2.7-3.7), and occurred at 40 milliseconds after IC (range, 0-83).

Conclusion: Based on when the sudden changes in joint angular motion and the peak vertical ground-reaction force occurred, it is likely that the anterior cruciate ligament injury occurred approximately 40 milliseconds after IC. The kinematic patterns were surprisingly consistent among the 10 cases. All players had immediate valgus motion within 40 milliseconds after IC. Moreover, the tibia rotated internally during the first 40 milliseconds and then external rotation was observed, possibly after the anterior cruciate ligament had torn. These results suggest that valgus loading is a contributing factor in the anterior cruciate ligament injury mechanism and that internal tibial rotation is coupled with valgus motion. Prevention programs should focus on acquiring a good cutting and landing technique with knee flexion and without valgus loading of the knee.

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