Research Review By Dr. Shawn Thistle©

Date Posted:

August 2009

Study Title:

Instrument-assisted cross-fiber massage accelerates knee ligament healing

Authors:

Lohgmani MT & Warden SJ

Author's Affiliations:

Department of Physical Therapy, Indiana University; USA.

Publication Information:

Journal of Orthopaedic & Sports Physical Therapy 2009; 39(7): 506-514.

Background Information:

Of all sporting injuries, roughly 50% involve a ligament, and the majority of these are capsular and extracapsular in nature (such as the knee and ankle collateral ligaments). It is generally accepted that ligament healing occurs via the formation of a reparative scar, rather than by regeneration. This can result in mechanical deficiencies and tissue weakness that, in combination with any neuromuscular deficits, may explain the high rate of re-injury. Readers should remember that the most significant risk factor for a ligament injury is a previous ligament injury.

Up to one third of patients who sustain ligament injuries still experience significant symptoms up to 3 years after the initial injury (1), and these injuries can also raise the risk of developing osteoarthritis (2).

In order to address the short- and long-term needs of patients who sustain capsular and extracapsular ligament injuries, there is a need to study simple clinical interventions that can be applied safely in a manual medicine setting. The goal of such treatments should be to accelerate or augment healing (to approximate pre-injury tissue status), improve clinical symptomatology, and reduce injury recurrence.

Cross-Fiber Massage (CFM) may be one such method for accelerating ligament healing. CFM refers to the application of forces specifically transverse to the direction of fibers of underlying collagen with the goal of inducing physiological and/or structural tissue changes. CFM involves little motion between the therapist’s contact and the skin, focusing instead on relative motion between the skin/subcutaneous tissue and the deeper connective tissues.

Recently the application of CFM has been enhanced by the introduction of rigid handheld instruments (most will be familiar with Graston, SASTM and the like) – the resultant technique will be referred to here as “Instrument-assisted CMF”, or IACFM. To date, the evidence surrounding these tools includes mainly case reports which for the most part have been positive (as case reports tend to be).

Based on the positive preliminary clinical reports and the proposed mechanical mode of action of IACFM, this study aimed to examine the short and longer-term effects of IACFM on tissue level healing of knee medial collateral ligaments (MCL) in an established animal model (Sprague-Dawley rats).

Pertinent Results:

  • all surgically induced ligament tears were bridged with scar tissue on harvesting (thickened, translucent, pinkish tissue)
  • at 12 weeks, ligaments had more whitish scars that were difficult to see, and the thickness at the injured area was continuous with the uninjured area
  • at 4 weeks post-injury - IACFM-treated ligaments were 43.1% stronger (p < 0.05), 39.7% stiffer (p < 0.05), and could absorb 57.1% more energy before failure (p < 0.05) than contralateral, injured, non-treated ligaments
  • at 12 weeks, there were minimal differences between IACFM-treated and non-treated ligaments, however the IACFM-treated ligaments were 15.4% stiffer (p < 0.05)
  • on examination of histological preparations and electron miscroscopic scans, IACFM-treated ligaments appeared to have improved collagen bundle orientation within the scar region compared to untreated ligaments
  • overall, it seems that IACFM promotes early tissue-level healing but does little in terms of augmenting long-term healing

Clinical Application & Conclusions:

In summary, this study suggests through an animal model that IACFM may accelerate early tissue healing following acute capsular/extracapsular ligament injury, however the longer-term effects seem to be minimal. This supports the theoretically sound argument that IACFM could be used in the early phases of treatment after ligament injury, but care should be taken to acknowledge the inherent limitations in this study design. Further trials in humans are necessary, and certainly warranted based on these results.

Currently there are limited treatment options to mediate tissue-level healing in ligaments. In the early phases when joint motion should be minimized, IACFM represents a simple and practical therapeutic technique that does not take much time to apply. In conjunction with other manual therapies, ligament healing and tissue-level biomechanical properties can hopefully be improved.

Study Methods:

This study employed a well-established animal model utilizing Sprague-Dawley rats (body mass 280-300g, purchased from Harlan Sprague-Dawley, Indianapolis IN). 51 animals underwent surgery to impart bilateral MCL injuries to their hindlimbs, while 7 remained as uninjured controls. The resulting injuries were complete disruptions of the MCL at its mid-substance and transverse to the underlying fiber alignment (no ligament material was removed and the ends were juxtaposed but not sutured). All animals demonstrated symmetrical hindlimb use after surgery and were allowed normal cage access (no exercise wheels) for the duration of the study.

Intervention – IACFM:
  • performed using a Graston tool (GT-6) – designed to apply force through its tip to small structures (in humans it would be used for finger joint capsules/collateral ligaments and other similar areas)
  • IACFM was initiated one week after surgery to allow post-surgical inflammation to abate
  • only the left MCL was treated in all groups (to allow the other to act as a control) and IACFM was performed for 1 minute treatments with the animals under anesthesia
  • approximately 250-300g of downward pressure was applied to the tool (therapists practiced on a force plate)
  • 31 injured animals were treated 3x/week for 3 weeks (9 total treatments), while the other 20 injured animals were treated 3x/week for 10 weeks (30 total treatments)
The primary outcome of interest in this study was the mechanical properties of the healing ligaments and how IACFM influenced this process. All animals were euthanized at either 4 weeks (the 9 treatment animals and 2 controls) or 12 weeks (the 30 treatment animals and 5 controls). Mechanical and histological testing were performed on all ligaments. Specimens were prepared and examined using previously published methods (the full descriptions are beyond the scope of this review). In addition, scanning electron microscopy and histological analysis were performed to assess ligament morphology.

Statistical comparisons were all 2-tailed. Unpaired t-tests were utilized to assess time (4 vs. 12 weeks post-injury) and group (injured vs. control); while paired t-tests were used to confirm mean percent differences between IACFM treated and non-treated MCLs.

Study Strengths / Weaknesses:

This study was well done overall and demonstrated some very interesting results that should stimulate further research – but the results should be considered in light of the following limitations:
  • most importantly and obviously, this is an animal study – this model is however highly reproducible and established in preclinical testing of treatment interventions for ligament injuries
  • this study did not assess how IACFM facilitates restoration of mechanical ligament properties
  • the size of rodent tissues in relation to humans raises scaling issues – the authors addressed this by using a tool commonly used in the treatment of smaller human ligaments
  • between-animal activity differences may have influenced the results, however this was combated in this study by using a within-animal control (the contralateral side)
  • this study could obviously not measure clinical outcomes such as pain

Additional References:

  1. van Rijn RM et al. What is the clinical course of acute ankle sprains? A systematic literature review. Am J Medicine 2008; 121: 324.331.
  2. Valderrabano V et al. Ligamentous post-traumatic ankle osteoarthritis. Am J Sports Med 2006; 34: 612-620.