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Date Posted:

February 2011

Study Title:

High-Field Magnetic Resonance Imaging Assessment of Articular Cartilage Before and After Marathon Running: Does Long-Distance Running Lead to Cartilage Damage?

Authors:

Luke AC, Stehling C, Stahl R et al.

Author's Affiliations:

Department of Orthopaedic Surgery and Department of Radiology, University of California, San Francisco, California; Department of Clinical Radiology, University of Muenster, Germany; Department of Clinical Radiology, University Hospitals—Campus Grosshadern, Ludwig Maximilians University of Munich, Germany; Albany Medical College, Albany, New York.

Publication Information:

American Journal of Sports Medicine 2010; 38: 2273-2280.

Background Information:

There is continuing controversy surrounding long-distance running and whether it results in irreversible articular damage. Over 30 million individuals participate in long-distance running such as marathons each year, and many of these participants will be first-time runners of all ages. With the large number of inexperienced runners, there is also a large incidence of running-related injuries.

In healthy cartilage, a continuous balance between the synthesis and breakdown of the cartilage matrix is required. On a biochemical level, marathon runners have demonstrated increased levels of inflammatory markers within 24 hours of completing a marathon.

Previous studies evaluating the effects of marathon running on knee structures using MRI have found differing results. While some studies showed no significant changes in knee structure, others showed transient changes in meniscal structure and subtle joint effusions. New quantitative MRI techniques have been developed to better assess possible biomechanical degradation using T1ρ and T2. Briefly, MRI uses magnetic fields and radio frequencies to change the alignment and spin of subatomic particles. Relaxation time refers to the amount of time taken for protons aligned by the magnetics and altered by the radiofrequency to return to their original alignment. Higher relaxation times indicate changes to the structure of the articular cartilage, which may indicate damage.
  • T1ρ has been proposed for detecting damage to the cartilage collagen-proteoglycan (PG) matrix.
  • T2 signals reflect collagen matrix orientation, water content and collagen degradation, which are also associated with cartilage degradation.
The objective of this study was to investigate the effects of long-distance marathon running on articular cartilage biochemical composition using high-field quantitative MRI.

Pertinent Results:

There were significant changes in T1ρ values in the experimental running group at some cartilage locations at 48-hours post-marathon (Post-marathon) and at 3 months post-marathon (Three months). Mean intra-group values for the experimental running group are presented with all values in milliseconds. P values below compare respective value with mean baseline value.
  • Patella: Baseline 38.4, Post-marathon 40.1 (P=0.011, significant increase), Three months 40.3 (P=0.007, significant increase).
  • Trochlea: Baseline 41.3, Post-marathon 43.6 (P=0.036, significant increase), Three months 43.7 (P=0.027, significant increase).
  • Medial femoral condyle: Baseline 35.9, Post-marathon 38.4 (P=0.023, significant increase), Three months 38.2 (P=0.002, significant increase).
  • Medial tibia: Baseline 32.4, Post-marathon 34.9 (P=0.002, significant increase), Three months 34.4 (P=0.022, significant increase).
  • Increases in T1ρ values in the lateral compartment were not significant.
Significant elevation of post-marathon and three month T1ρ values indicate little recovery in changes to the cartilage PG matrix.

There were significant changes in T2 values in the experimental running group at some cartilage locations at 48-hours post-marathon (Post-marathon), but fewer at 3 months post-marathon (Three months). Mean intra-group values for the experimental running group are presented with all values in milliseconds. P values below compare respective value with mean baseline value.
  • Patella: Baseline 31.7, Post-marathon 33.3 (P=0.010, significant increase), Three months 32.6 (P=0.109).
  • Trochlea: Baseline 32.6, Post-marathon 34.6 (P=0.008, significant increase), Three months 32.9 (P=0.626).
  • Medial femoral condyle: Baseline 29.1, Post-marathon 30.3 (P=0.018, significant increase), Three months 30.1 (P=0.018, significant increase).
  • Medial tibia: Baseline 25.7, Post-marathon 27.7 (P=0.021, significant increase), Three months 25.3 (P=0.736, significant increase).
  • Increases in T2 values in the lateral compartment were not significant.
Significant increases at the post-marathon scan and predominant return to near-baseline levels at three months indicated possible short-term damage but long-term recovery in water content and fluid shifts, as well as collagen degradation.

T1ρ and T2 values strongly correlated (Correlation coefficient = 0.81, P < 0.001).

Controls had no significant differences between baseline and three month scans in T1ρ (P=0.821) or T2 (P=0.674) values.

Intergroup comparisons revealed significant differences between the experimental running group and the control group at some time points but not at others.
  • There were no intergroup differences in T1ρ (37.0 ms ± 4.4 versus 36.8 ms ± 4.1; P = 0.660) or T2 (29.4 ms ± 3.9 versus 28.9 ms ± 3.8; P = 0.258) values at baseline.
  • Average three month T1ρ vales remained significantly elevated in runners compared with controls (39.0 ms ± 4.5 versus 36.7 ms ± 4.2, P = 0.003).
  • Average three month T2 values showed no significant differences (29.4 ms ± 3.9 versus 28.9 ms ± 3.8, P = 0.258).
No gross morphological changes such as meniscal tears or extrusions, joint effusion, subchondral or periarticular cysts, loose bodies, or impaired integrity of the collateral and cruciate ligaments, were noted in either group at baseline and at follow-up (post-marathon and three month scans).

Clinical Application & Conclusions:

This study found that long distance running causes biochemical changes in articular cartilage in the knee, including fluid shifts in the cartilage matrix, demonstrated by increasing and recovering T2 values, and elevated T1ρ values. As baseline values for each were similar between groups, it is thought that the load from running the marathon was responsible for the T1ρ changes seen at the three month scan in runners. T2 values predominantly returned to near-baseline levels with a decrease in running load after the marathon, which is promising evidence that marathon running does not result in persistence fluid changes, and that the articular cartilage matrix recovers and maintains functional and structural properties after a marathon load.

No major structural changes were observed post-marathon in the runners. The load from running the marathon did not cause acute, structural defects in the articular cartilage in knees with normal anatomy.

It should be noted that changes in T1ρ and T2 values were greatest in the medial compartment and the patellofemoral joints. This may indicate more than transient and reversible fluid shifts, but whether post-marathon T1ρ and T2 changes lead to damaging structural articular cartilage changes over time requires longer term studies.

Study Methods:

  • Cohort study between marathon runners (n = 10) and age, sex, and body mass index (BMI) matched controls (n = 10).
  • Participants were between 18 and 40 years old.
  • Inclusion criteria for the runners were: no more than three marathons run previously and none in the last four months, no history of knee pain, no history of lower extremity surgery, no decrease in training habits due to injury before the marathon, and a BMI of less than 30.
  • Controls had no history of marathon running and on average exercised less than 30 minutes per day.
  • Baseline descriptive information was obtained using a self-reported pre-participation history and a musculoskeletal screening. Runners provided details of their training volumes and methods on a questionnaire at their first MRI, within two weeks before the marathon. All runners underwent a taper period of at least two weeks before the marathon and confirmed they had no plans to do any marathon training within three months after the race.
  • Runners and controls had a 3.0-T system MRI scan on the dominant knee within two weeks prior to the marathon. Runners had a post-marathon scan 48 hours after completing the marathon, and runners and controls had a follow up scan three months after the marathon.
  • All MRI images were reviewed by two radiologists with 20 and five years of experience in musculoskeletal imaging who were blinded to MRI sequencing and experimental or control groups. Image quality and pathologic findings were assessed independently.
  • Statistical significance was set at P < 0.05.
  • Demographic information including age, height, weight, BMI and sex were compared for differences using t tests.
  • Comparisons of T1ρ and T2 MRI values were made using paired t tests, including runners at baseline, post-marathon, and at three months.
  • Paired t tests were used to compare T1ρ and T2 MRI values between runners and controls at baseline and at three months.
  • T1ρ and T2 data were assessed for correlation using a scatter plot and linear regression model.

Study Strengths / Weaknesses:

Strengths:
  • The experimental running group was defined to represent younger, less experienced marathon runners, rather than experienced runners.
  • The control group was matched for age, sex and BMI.
  • A prospective 3-month time course was followed.
Weaknesses:
  • The subject groups were relatively small (n = 10 for both experimental and control).
  • The inclusion of experienced runners may have resulted in different findings.
  • A longer study period may have shown different T2 reactions.
  • Different results may have been shown if the runners had continued long distance marathon training after the marathon.

Additional References:

  1. Foley S, Ding C, Cicuttini F, et al. Physical activity and knee structural change: a longitudinal study using MRI. Med Sci Sports Exerc. 2007; 39(3):426-434.
  2. Krampla W, Mayrhofer R, Malcher J, et al. MR imaging of the knee in marathon runners before and after competition. Skeletal Radiol. 2001; 30(2): 72-76.
  3. Taunton JE, Ryan MB, Clement DB, et al. A prospective study of running injuries: the Vancouver Sun Run “In Training” clinics. Br J Sports Med. 2003; 37(3): 239-244.

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