Associations between isolated bundle tear of anterior cruciate ligament, time from injury to surgery, and clinical tests

Loading mechanisms of the anterior cruciate ligament

This review identifies the three-dimensional knee loads that have the highest risk of injuring the anterior cruciate ligament (ACL) in the athlete. It is the combination of the muscular resistance to a large knee flexion moment, an external reaction force generating knee compression, an internal tibial torque, and a knee abduction moment during a single-leg athletic manoeuvre such as landing from a jump, abruptly changing direction, or rapidly decelerating that results in the greatest ACL loads. While there is consensus that an anterior tibial shear force is the primary ACL loading mechanism, controversy exists regarding the secondary order of importance of transverse-plane and frontal-plane loading in ACL injury scenarios. Large knee compression forces combined with a posteriorly and inferiorly sloped tibial plateau, especially the lateral plateau-an important ACL injury risk factor-causes anterior tibial translation and internal tibial rotation, which increases ACL loading. Furthermore, while the ACL can fail under a single supramaximal loading cycle, recent evidence shows that it can also fail following repeated submaximal loading cycles due to microdamage accumulating in the ligament with each cycle. This challenges the existing dogma that non-contact ACL injuries are predominantly due to a single manoeuvre that catastrophically overloads the ACL.

The diagnostic accuracy of clinical tests for anterior cruciate ligament tears are comparable but the Lachman test has been previously overestimated: a systematic review and meta-analysis

PURPOSE

The diagnostic accuracy of clinical tests for anterior cruciate ligament injury has been reported in previous systematic reviews. Numerous studies in these reviews include subjects with additional knee ligament injury, which could affect the sensitivity of the tests. Meta-analyses have also been performed using methods that do not account for the non-independence of sensitivity and specificity, potentially overestimating diagnostic accuracy. The aim of this study was to report the diagnostic accuracy of clinical tests for anterior cruciate ligament tears (partial and complete) without concomitant knee ligament injury.

METHODS

A systematic review with meta-analysis was performed according to the PRISMA guidelines. Meta-analyses included studies reporting the specificity and/or sensitivity of tests with or without concomitant meniscal injury. Where possible, pooled diagnostic estimates were calculated with bivariate random-effects modelling to determine the most accurate effect sizes. Diagnostic accuracy values are presented for the anterior drawer, Lachman, Lever sign and pivot shift tests overall and in acute or post-acute presentations.

RESULTS

Pooled estimates using a bivariate model for overall sensitivity and specificity respectively were as follows: anterior drawer test 83% [95% CI, 77-88] and 85% [95% CI, 64-95]; Lachman test 81% [95% CI, 73-87] and 85% [95% CI, 73-92]; pivot shift test 55% [95% CI, 47-62] and 94% [95% CI, 88-97]; Lever sign test 83% [95% CI, 68-92] and 91% [95% CI, 83-95]. For specific presentations, the sensitivity and specificity of the Lachman test, respectively, were: complete tears 68% [95% CI, 54-79] and 79% [95% CI, 51-93]; post-acute injuries 70% [95% CI, 57-80] and 77% [95% CI, 53-91].

CONCLUSIONS

The pivot shift and Lever sign were the best tests overall for ruling in or ruling out an anterior cruciate ligament tear, respectively. The diagnostic accuracy of the Lachman test, particularly in post-acute presentations and for complete tears, is lower than previously reported. Further research is required to establish more accurate estimates for the Lachman test in acute presentations and partial ligament tears using bivariate analysis.

LEVEL OF EVIDENCE

III.

Knee injuries concomitant to posterior acetabular fractures: an association to look for

PURPOSE

Acetabular fractures are frequently associated with other skeletal injuries, particularly knee injuries. This study aims to evaluate the relationship between posterior acetabular fractures and knee injury, analyzing its patterns and association with other injuries.

METHODS

This is a retrospective monocentric study in a tertiary referral centre. We reviewed the data (age, sex, type of fracture, and concomitant injury) of patients hospitalized for a posterior acetabular fracture. We recorded concomitant knee injury diagnosed up to one year following acetabular fracture.

RESULTS

Two-hundred-seventeen patients (177 males/40 females) were included. The mean age was 40.5 years. Eighty-five patients (39%) had a concomitant hip dislocation, nine (4.1%) had sciatic nerve palsy, 17 (7.8%) had upper extremity injury, and 18 (8.3%) had lower extremity injury (other than the knee). Eight (3.7%) patients had spine injury, 11 (5.1%) had severe thoracic injury, nine (4.1%) had an abdominal injury, and four (1.8%) had a head injury. There were 33 (15.21%, 95% CI 10.80-20.8%) patients (30 M/3 F) (group 1) with a concomitant knee injury and 184 patients without a concomitant knee injury(group 2). The mean age in group 1 was 34.3 compared to 45.4 in group 2(p = 0.021). The pattern analysis revealed five fractures, 14 ligamentous injuries (PCL injuries = 68%), and 14 soft tissue injuries. Sixteen (48.48%) injuries were identified during hospitalization and 17 (51.51%) during follow-up. There were an association between knee injury and upper extremity injury (OR = 3.49 95% CI 1.12-10.00,p = 0.022) and other lower extremity injury (OR = 3.18 95% CI 1.03-8.95,p = 0.032).

DISCUSSION

Knee injury is the second most frequent lesion associated with posterior acetabular fractures. Being missed in half of cases, we recommend a systematic examination of ipsilateral knees under general anaesthesia, keeping a high index of suspicion and a low threshold for complementary knee imaging. Knee injury should be mainly looked for in patients younger than 60 years and in those with upper and/or lower extremities injuries.

Knee Injury Associated With Acetabular Fractures: A Multicenter Study of 1273 Patients

OBJECTIVES

The purpose of this study was to determine the incidence and pattern of the knee injury associated with acetabular fractures.

DESIGN

Retrospective cohort study.

SETTING

Three level I and one level II trauma centers.

PATIENTS

A total of 1273 skeletally mature patients treated at 4 trauma centers between November 2004 and December 2013 for acetabular fractures were retrospectively identified from orthopaedic trauma databases.

INTERVENTION

Analysis of all acetabular fractures with knee injury regarding type of acetabular fracture, mechanism of injury, energy of injury, pattern of the knee injury, knee examination findings at initial presentation, intraoperative and on follow-up, requirement for surgery/conservative management, and the associated injuries. The clinical data entered during inpatient stay and office visits were analyzed.

MAIN OUTCOME MEASURES

Incidence and pattern of the knee injury.

RESULTS

One hundred ninety-three of 1273 patients (15%) were found to have ipsilateral knee symptoms within a period of 1 year from the date of injury. The patterns of knee injury included 56 fractures (29%), 49 ligamentous lesions (25%), and 88 miscellaneous (46%) causes including bone bruises, wounds, and swelling. Associated injuries included 85 patients with ipsilateral hip dislocation (45%), 59 pelvic injuries (31%), 61 extremity injuries (32%), 38 head injuries (20%), 37 chest injuries (20%), 23 abdominal and genitourinary injuries (12%), and 7 injuries of the spine (4%).

CONCLUSION

Based on this study, we conclude that knee injuries associated with high-energy acetabular fractures constitute a significant portion of the patient population. Ligament injuries are frequently overlooked and thorough clinical evaluation and utilization of magnetic resonance imaging in selected cases will help in early detection and prevention of long-term complications.

LEVEL OF EVIDENCE

Prognostic Level IV. See Instructions for Authors for a complete description of levels of evidence.