Research Review By Dr. Brynne Stainsby©

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Date Posted:

August 2018

Study Title:

Is core stability a risk factor for lower extremity injuries in an athletic population? A systematic review

Authors:

De Blaiser C, Roosen P, Willems T et al.

Author's Affiliations:

Department of Rehabilitation Sciences and Physiotherapy, Ghent University, Ghent, Belgium; Department of Physical and Rehabilitation Medicine, Ghent University Hospital, Ghent, Belgium.

Publication Information:

Physical Therapy in Sport 2018; 30: 48-56.

Background Information:

While physical activity is widely recommended as a positive health behaviour, participation in sport and activity involves the risk of musculoskeletal injury, particularly in the lower extremity (1). While risk factors such as altered knee biomechanics have been studied, little is known about the role of core stability and the development of injuries (2-4). Core stability is generally defined as the foundation of lumbopelvic motor control to allow for optimal production and modulation of force that is transferred through the kinetic chain during movement (5, 6).

Core stability is a dynamic process, which requires the integration of muscular strength and endurance, proprioception and neuromuscular control (7-9).

Given the importance of understanding if core stability may be a risk factor for lower extremity injury, the purpose of this systematic review was to summarize the literature in this field, and to generate future hypotheses regarding injury prevention.

Pertinent Results:

Literature Search Results:
  • A total of 1580 citations were retrieved, 1253 titles and abstracts were screened for eligibility and 14 potentially relevant articles were identified for full-text screening and critical appraisal.
  • Nine studies were included in the review (3, 4, 8-14).
  • All included studies had a prospective cohort design.
Core Endurance and Lower Extremity Injuries:

Three studies investigated the relationship between core endurance and lower extremity injuries (4, 10, 12). When comparing injured versus uninjured athletes:
  1. In one study, no significant differences were found on the duration of hold in the anterior, posterior and lateral core muscle endurance tests (10).
  2. In the other two studies, no significant differences in endurance times were found between injured and uninjured athletes; however, significantly lower endurance times were found when testing anterior core endurance of injured athletes when compared to uninjured. Further, decreased anterior core endurance was found to be a modifiable risk factor in injury prediction models (4, 12).
  3. Overall, there was no evidence which demonstrated a difference in hold times when testing posterior and lateral core muscle endurance in injured versus uninjured athletes, and conflicting evidence regarding anterior core muscle endurance (4, 10, 12).
Core Strength and Lower Extremity Injuries:

One study investigated the relationship between core muscle strength and ACL injuries specifically (3):
  1. Maximum absolute and maximum relative isometric strength were measured for trunk flexion and extension, and trunk strength balance was calculated as the index of the ratio of absolute flexion to extension strength (3).
  2. Significant differences were found in absolute strength, relative strength and strength balance between injured and uninjured athletes, thus, these variables may be considered risk factors for ACL injuries (3).
Core Proprioception and Lower Extremity Injuries:

One study investigated the role of proprioception, measured by active and passive repositioning of the lumbar spine (9):
  1. The difference between starting and ending position of the trunk during active and passive repositioning tasks was measured in degrees, and deviations from 0° were described as deficits in repositioning sense (9).
  2. Significant differences were found in female athletes with knee injuries, though this finding was not observed in male athletes. Active proprioceptive repositioning deficits were also found to be a risk factor for knee injuries in female athletes (though not males) (9).
Core Neuromuscular Control and Lower Extremity Injuries:

Four studies investigated neuromuscular control by studying movement of the lumbopelvic region during specific tasks (8, 11, 13, 14):
  1. Two studies assessed uncontrolled displacement of the lumbopelvic region (measured in degrees) during single leg drop landing (13, 14). These studies found some evidence for increased displacement in the transverse plane of the ipsilateral hip, pelvis and trunk to be a risk factor in females who developed exertional medial tibial pain (13, 14).
  2. Another study investigated quick force release after isometric trunk exertion and found the total displacement of the trunk after sudden force release was significantly greater in athletes who developed a knee injury (8). Based on an injury prediction model, coronal and sagittal displacement of the trunk were predictors of knee injury in female athletes (not males) (8).
  3. The fourth study assessed control of the lumbopelvic region while performing dynamic tests and found some evidence that reduced movement control in dancers was associated with an increased risk of developing lower extremity injuries (11).

Clinical Application & Conclusions:

This review identified the potential relationship between core stability and lower extremity injuries in athletes. Although this review specifically examined the athletic population, the results may be even more profound in the general population with decreased levels of overall conditioning and motor control (this concept requires further research). The evidence suggests that core endurance, strength, proprioception and neuromuscular control may be risk factors in the development of lower extremity injuries, particularly in females. Future research is needed to identify the role anterior core muscle endurance may play in these injuries.

As the studies included in this review were observational in nature, no conclusions may be drawn regarding how clinicians may implement core strength, proprioceptive or neuromuscular control training into their practices based on this paper. Clinicians would be advised to follow best practices of training and patient preferences when incorporating exercises into their management plans.

Importantly, it should also be noted that comments regarding safety could not be made in this review, given the cohort design of the included studies. Again, clinicians should look at the overall body of evidence regarding exercise, which generally demonstrates only short-lived, minor adverse events; namely, post-treatment soreness (15). Patients should be advised of this potential, but encouraged to remain compliant with training programs.

Study Methods:

  • This review followed the Preferred Reporting Items for Systematic reviews and Meta-analysis (PRISMA) guidelines.
  • Web of Science, PubMed and the Embase Libraries were searched up to August 2016, using appropriate search terms for each database. Reference lists of relevant guidelines were screened for additional resources. Finally, hand searches were performed by searching the reference lists in relevant studies.
  • Two authors independently screened titles and abstracts for inclusion.
  • Studies evaluating core stability as a risk factor in the development of lower extremity injuries in a population of healthy, athletic subjects were included in this review. Expert opinions, case reports and reviews were also included.
  • Inclusion criteria: studies had to report on at least one objective measure of core stability and/or neuromuscular control, injuries included acute or overuse injuries of the lower extremity, subjects must have been otherwise healthy and participating in competitive sport, collegiate sport or collegiate physical education studies, and articles must have been published in Dutch, French or English.
  • Risk of bias (methodological quality) was assessed using the Newcastle-Ottawa quality assessment scale for cohort studies (NOS). A quality score of 3/6 or 4/6 was considered moderate quality, whereas studies of 5/6 or 6/6 were deemed to be high quality. Studies with scores of less than 3/6 were excluded.
  • Data from included studies was extracted and merged into evidence tables.

Study Strengths / Weaknesses:

Strengths:
  • A thorough and systematic search.
  • Independent screening of titles and abstracts, and full texts.
  • Assessment of risk of bias was performed with a validated set of criteria.
  • Authors categorized the evidence when possible based on measurement technique and outcome studied.
  • The authors used the limitations of this review to provide suggestions regarding future research to improve the quality of evidence on this clinically important topic.
  • Only those studies assessed as moderate or high quality were included.
Weaknesses:
  • The primary limitation of this review relates more to the quality of the body of evidence than the methodology of the review itself.
  • Although the authors used a validated tool to assess risk of bias, studies of moderate quality (and thus moderate risk of bias) were included, and this means the findings must be interpreted with some degree of caution.
  • Though nine studies were included in the overall review, differences in measurement techniques, populations and outcomes limited the ability to draw strong conclusions from the data, and meta-analysis could not be performed.
  • The included studies did not fully describe the participants, which limits the external validity of the review.

Additional References:

  1. Bahr R and Krosshaug T. Understanding injury mechanisms: A key component of preventing injuries in sport. Br J Sports Med 2005; 39(6): 324-329.
  2. Chuter VH and Janse de Jonghe XA. Proximal and distal contributions to lower extremity injury: A review of the literature. Gait Posture 2012; 36(1): 7-15.
  3. Raschner C, Platzner H, Patterson C et al. The relationship between ACL injuries and physical fitness in young competitive ski racers: A 10-year longitudinal study. Br J Sports Med 2012; 46(15): 1065-1071.
  4. Wilkerson GB and Colstan MA. A refined prediction model for core and lower extremity sprains and strains among collegiate football players. J Athl Train 2015; 50(6): 643-650.
  5. Ireland ML, Willson JD, Ballantyne BT et al. Hip strength in females with and without patellofemoral pain. J Orthop Sports Phys Ther 2003; 33(11): 671-676.
  6. Kibler WB, Press J and Sciascia A. The role of core stability in athletic function. Sports Med 2006; 36(3): 189-198.
  7. Borghuis J, Hof A and Lemmink KAPM. The importance of sensorymotor control in providing core stability: Implications for measurement and training. Sports Med 2008; 38(11): 893-916.
  8. Zazulak BT, Hewett TE, Reeves NP et al. Deficits in neuromuscular control of the trunk predict knee injury risk. The Am J Sports Med 2007a; 35(7): 1123-1130.
  9. Zazulak BT, Hewett TE, Reeves NP et al. The effects of core proprioception on knee injury. A J Sports Med 2007b; 35(3): 368-373.
  10. Leetun DT, Ireland ML, Willson JD et al. Core stability measures as risk factors for lower extremity injury in athletes. Med Sci Sports Ex 2004; 36(6): 926-934.
  11. Roussel NA, Nijs J, Mottram S et al. Altered lumbopelvic movement control but not generalized joint hypermobility is associated with increased injury in dancers. A prospective study. Man Ther 2009; 14(6): 630-635.
  12. Wilkerson GB, Giles JL and Seibel DK. Prediction of core and lower extremity strains and sprains in collegiate football players: A preliminary study. J Athl Train 2012; 47(30): 264-272.
  13. Verrelst R, De Clerq D, Vanrenterghem J et al. The role of proximal dynamic joint stability in the development of exertional medial tibial pain: A prospective study. Br J Sports Med 2013; 48(5): 388-393.
  14. Verrelst R, De Clerq D, Willems TM et al. Contralateral risk factors associated with exertional medial tibial pain in women. Med Sci Sports Ex 2014; 46(8): 1546-1553.
  15. Wong JJ, Cote P, Sutton DA et al. Clinical practice guidelines for the noninvasive management of low back pain: A systematic review by the Ontario Protocol for Traffic Injury Management (OPTIMa) Collaboration. Eur J Pain 2017; 21(2): 201-216.