Sports Medicine Research: In the Lab & In the Field: Predictors of Failure After ACL Reconstructions (Sports Med Res)


Monday, May 21, 2012

Predictors of Failure After ACL Reconstructions

Prospective analysis of failure rate and predictors of failure after anatomic anterior cruciate ligament reconstruction with allograft

Van Eck CF, Schkrohowsky JG, Working ZM, Irrgang JJ, Fu FH. Am J Sports Med. 2012 Apr 03.

Re-injury rates after ACL reconstruction (ACLR) are shockingly high, with up to 25% of patients suffering a re-injury.  Surgical advancements abound in attempting to decrease re-injury rates and the development of osteoarthritis after ACL injury, but highly structured prospective analysis of re-injury rates for each type of ACLR are not currently available.  Therefore, the purpose of this investigation was to systematically analyze the re-injury rate of patients undergoing an anatomic ACLR with allograft tissue, as well as to identify predictors of re-injury. Patients undergoing ACLR at the University of Pittsburgh Medical Center were prospectively enrolled in a registry and followed for up to 4 years. The outcomes of interest in this study were operational definitions of failure - 1) subjective complaints of instability, 2) > 5mm difference in arthrometry between limbs, 3) abnormal pivot-shift, or 4) re-rupture diagnosed on MRI or arthroscopy. Return to sport clearance was not granted until around 9 months post-operatively. A re-injury rate of 13% (13% double bundle ACLR vs. 11% in single bundle ACLR) was observed in this cohort. Age (younger than 19) and earlier return to sport (222 days vs. 267 days or 7m v 9m) were associated with graft failure.

For all of the talk about the potential for anatomic ACLR or double-bundle ACLR to improve outcomes after injury, these results put newer methods right on par with previously established methods.  The authors propose (and the numbers support) that timing of return to sport may need to be adjusted with an anatomic allograft ACLR to prevent re-injury (and hopefully restore normal biomechanics). Without graft source morbidity (anterior knee pain with patellar tendon graphs; hamstring weakness with hamstring grafts), which invariably delays rehabilitation, patients with an allograft may simply feel too good and do too much, too soon.  However, with long term deficits in strength that can result from autograft harvest, an allograft has many advantages.  The one thing that is frequently overlooked in the re-injury literature is the measured functional capability of patients returning to sport after ACL reconstruction (Barber-Westin, Phys Sportsmed 2011).  Leading European researchers have recommended extremely high levels of measured functional test symmetry before returning to sport (Thomee, KSSTA 2011), but we do not see any mention of objective testing in this cohort of patients. The authors mention that many athletes return to sport without express clearance of their surgeon, which is clearly a concern for patients returning to sport before they are ready.  But another question is how many patients are cleared for sport before they are physically ready? Ligamentization does not occur for nearly a year, but we see many players return to sport before one year without any issues - what makes them different than those who re-injure? And more importantly, can we identify them without sophisticated and cost-prohibitive biomechanical analysis?  Do you have a separate protocol for patients who have had an ACLR with an allograft or an anatomic ACLR? Or do you treat them the same and allow them to return when the numbers show they are performing symmetrically? What are the red flags that you look for in a patient after ACLR?

Written by: Andrew Lynch
Reviewed by:  Stephen Thomas

Related Posts:

van Eck CF, Schkrohowsky JG, Working ZM, Irrgang JJ, & Fu FH (2012). Prospective analysis of failure rate and predictors of failure after anatomic anterior cruciate ligament reconstruction with allograft. The American Journal of Sports Medicine, 40 (4), 800-7 PMID: 22238055


Kale Songy said...

I found it interesting that there was a greater re-injury rate for the double bundle procedure versus the single bundle procedure. These percentages were close (13% vs 11%) and there is always the possibility of the numbers changing with a larger sample size. Still, it would be interesting to study the correlation of double-bundle procedures with re-injury rate versus the single-bundle procedure.
I think that the associations of age and earlier return to sport with graft failure were very important findings. It reinforces the focus during rehabilitation to tissue healing and maximum functionality, instead of the fastest return-to-play possible, and granting it after gaining the minimal functionality necessary.

Andrew Lynch said...

Tissue healing and maximal functionality are clearly important issues to consider when returning any athlete to sport after surgical intervention, however, they are constantly weighed against the utilization of rehabilitation. There is a glaring need for improved rehabilitation protocols that emphasize early professionally guided self-management which allows for later skilled intervention in the return to sport phase - a phase when many athletes are released to coaches or others who have knowledge of improving sport performance but lack experience in injury prevention. A lack of objectively validated return to play criteria which minimize risk of re-injury also contribute to these poor outcomes.

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