The use of slice encoding for metal artifact correction (SEMAC) sequencing improves the diagnostic evaluation of graft integrity following anterior cruciate ligament reconstruction

OBJECTIVES

To determine whether magnetic resonance imaging (MRI) with metal artifact reduction sequencing is superior to conventional knee MRI in the evaluation of an injured anterior cruciate ligament (ACL) graft, where visualisation on conventional MRI can be limited by the metal artifact from fixation devices.

METHODS

Eighteen patients underwent conventional MRI sequence (proton density fat saturated [PDFS]) and two types of metal artifact reduction sequencing MRI (WARP, slice encoding for metal artifact correction (SEMAC); Siemens) following a secondary injury to their ACL reconstructed knee. Six raters with experience in knee MRI evaluation reviewed sagittal PDFS, WARP, and SEMAC sequences, providing semi-quantitative grades for visualisation and diagnostic confidence assessing the ACL, posterior cruciate ligament , menisci, tibial and femoral tunnel margins, and articular cartilage. Intra-class correlation coefficients for inter-rater reliability were evaluated. The 6-rater mean scores for the visualisation and diagnostic confidence derived from each sequence were compared using the Friedman test for multiple paired samples.

RESULTS

No statistically significant difference in the ACL visualisation among the sequences was found (p ​= ​0.193). Further, a subgroup analysis was performed in cases evaluated as "moderately blurry" or "indistinct ACL visualisation" on PDFS (58% of cases). SEMAC significantly improved diagnostic confidence in ACL visualisation (p ​= ​0.041) and ACL graft rupture (p ​= ​0.044) compared to PDFS. There was no statistically significant difference in the inter-observer reliability between sequences. The WARP sequence added 2.84 ​± ​0.69 ​min, while SEMAC added 2.95 ​± ​0.40 ​min to the standard knee MRI scan time.

CONCLUSION

use of the SEMAC metal reduction sequence significantly improved diagnostic accuracy and confidence in the detection of ACL graft rupture in cases where the ACL was moderately blurry or indistinct on the PDFS sequence. This sequence should be considered as an adjunct to conventional PDFS in cases where graft visualisation is limited by the metal artifact from fixation devices.

LEVEL OF EVIDENCE

III.

Microfracture of Articular Cartilage

Microfracture is a treatment option for symptomatic, full-thickness cartilage defects. Microfracture is most likely to be successful when performed in nonobese patients under the age of thirty years for small (<2 to 4-cm2) femoral condylar defects that have been symptomatic for a short time (less than twelve to twenty-four months). Microfracture has acceptable short-term clinical results, but results can be expected to decline over time. Long-term studies that compare microfracture with advanced cartilage restoration techniques are required to ascertain whether these newer techniques provide longer-lasting results.

Anterior Knee Impingement in a High-Level Football Punter: A Case Report and Description of the Active-Passive Knee Extension Test

A 22-year-old football punter complained of anterior knee pain deep to his patellar tendon that occurred every time the knee of his kicking leg reached full extension during a punt. Arthroscopy confirmed anterior impingement between a fibrous tissue eminence directly anterior to his anterior cruciate ligament (ACL) and the intercondylar roof in full extension. With the eminence removed, full extension no longer caused impingement as demonstrated arthroscopically. He resumed punting at maximal effort 6 weeks postoperatively without pain. We report the active-passive knee extension test, a physical examination maneuver designed to identify patients with anterior knee impingement between tissue anterior to the ACL and the intercondylar roof. This test is a helpful part of the clinical examination in detecting these lesions.

The Relationship between Body Mass Index and Risk of Failure following Meniscus Repair

It is unknown whether body mass index (BMI) influences outcomes of meniscus repair. We hypothesized that increased BMI would be associated with increased risk of failure. A retrospective study was performed involving patients who had undergone meniscus repair between 2008 and 2012. Chart review and phone interviews were conducted to determine which patients required additional surgery. Patients were categorized as normal BMI (<25) or increased BMI (≥25). Of the 305 patients who met study criteria, 216 (70.8%) were available for follow-up at a mean of 19 months postoperatively. A total of 100 patients (46.3%) had a BMI <25 and 116 (53.7%) patients had a BMI ≥25. BMI was less than 35 in 90% of patients. Thirty-four patients (15.7%) required further surgery for a repair failure. Failure occurred in 20 patients (20%) in the normal BMI group and 14 patients (12%) in the increased BMI group (p = 0.14). Logistic regression revealed a trend toward decreased odds of repair failure in the increased BMI group (odds ratio: 0.46; 95% confidence interval: 0.20-1.05; p = 0.065). Patients with a BMI ≥25 did not have a higher risk of meniscus repair failure relative to those with a BMI <25. Given these findings, surgeons should not consider moderately increased BMI as a contraindication to meniscal repair. The effect of BMI greater than 35 on outcomes of meniscal repair remains unclear and warrants further study.

Ice hockey injuries among United States high school athletes from 2008/2009-2012/2013

BACKGROUND

The popularity of ice hockey has grown in recent years and injuries are a concern given the physical nature of the sport. We sought to report the rates, mechanisms, and severity of boys' US high school ice hockey injuries. We hypothesized that body checking would be a major source of injury and that concussions would be common. We also expected to find that competition would have a higher rate of injury than practice.

DESIGN

Descriptive epidemiology study.

METHODS

Boys' US high school ice hockey injury data from 2008/2009 through 2012/2013 academic years were obtained from the National High School Sports-Related Injury Surveillance System, High School Reporting Information Online database. The primary outcome was rate of injury per 10,000 athlete exposures (AEs).

RESULTS

Overall, 724 boys ice hockey injuries occurred during 311,817 AEs for an injury rate of 23.2 per 10,000 AEs. Injury rates were significantly higher during competition compared to practice (rate ratio = 7.8, 95% confidence interval: 6.5-9.4). Concussion was the most frequent injury reported at a rate of 6.4 per 10,000 AEs. Body checking was the mechanism of injury in over 46% of injuries. The head/face/neck region (33.8%) and upper arm/shoulder region (20.6%) were the most commonly injured body sites. Just over 6% of injuries resulted in surgical intervention.

CONCLUSION

Injuries among high school ice hockey athletes are common. Increases in the number of high school ice hockey injuries will likely parallel the increase in high school ice hockey participation in the United States.