This RCT was clearly provoked by the unresolved clinical controversy concerning "the best time" (post-injury) to perform an anterior cruciate ligament (ACL) reconstruction. Based mainly on evidence of a higher incidence of post-operative complications with early surgery, some have advocated delaying the surgery by anywhere from 2 to 12 weeks to mitigate those risks. However, others have suggested that reconstruction can be performed within that time frame without any notable problems and that such an approach is, in fact, preferred to optimize healing and to minimize total recovery time.
On its surface, like others,1 this paper clearly supports the latter view by demonstrating 'no difference' in patients randomized between 'early reconstruction' (2 to 14 days post-injury) and 'delayed reconstruction' (29 to 42 days post-injury) when followed for 26 to 36 months by five credible assessment methods. Further, they were applied appropriately by a blinded observer, achieving a desired 80% power level for the 'no difference' observation, (assuming a null hypothesis value of 50% and a 70% difference as being clinically significant). The duration of follow-up was reasonable and differences seem unlikely to emerge, making its results even more convincing for this population of patients.
However, like all RCT's, these observations need to be qualified to the criteria allowed by its inclusion and exclusion criteria and there are a few other considerations. Firstly, it is important to note that this study applies only to (MRI-confirmed) isolated first-time ACL injuries being treated with arthroscopic quadrupled hamstring reconstruction, as opposed to the other options available,2 and they were clearly done by a high volume surgeon in a controlled practice setting with similarly controlled (moderately aggressive) rehabilitation. Each of these factors probably affects the outcome.3
Importantly, there were apparently few if any non-compliant patients in this series, as all consented to be studied (a selection bias toward those compliant with rehabilitation) and only six were lost to follow-up. As noted above, the potential effects of rehabilitation on the recovery of movement should not be underestimated.3 Patients who do not want rehabilitation should not have an ACL reconstruction.
Secondly, it should be noted that patients with recurrent ACL injuries, knees with high-grade chondral injuries, those with repairable menisci, and those with MRI-confirmed combined ligament injuries were excluded. Each of these pathologies represents different patients encountered in real life, in which the timing of surgery may have different effects. They certainly cause increased variation of results, if nothing else.
Thirdly, it is worth pointing out that the definitions of early and delayed used here may not apply to all practice settings. In our centre, for example, the time from first injury to ACL reconstruction of less than 42 days (their longest interval) would be unusual, as we currently lack a community screening system with such an accurate early diagnosis with MRI confirmation and rapid access to operating facilities. These delays certainly change the situation, since we more frequently have non-rehabilitated ACL deficient patients presenting with stiff and weak knees a few weeks post-injury. As a principle, we have always thought it wise to attempt to regain a nearly full passive range of movement before embarking on an ACL reconstruction, regardless of when it has presented post-injury. Excluding locked knees, restoring movement through rehabilitation before the ACL reconstruction would seem to be advisable.
Finally, the whole notion that changes in the timing of reconstructive surgery may have clinical significance begs the question: "What are the mechanisms by which early versus late surgery that is identical in every other way might alter outcomes"? Does the timing of surgery, interacting with age or gender-related factors, other co-morbidities, combined ligament and meniscal damage or perhaps injuries with concomitant chondral injury somehow alter the biological processes of repair in a joint and perhaps predispose to aberrant inflammation or to aggressive intra-articular scars and thus, arthrofibrosis'? While there is some knowledge about the possibilities, little is currently know about the influence of these factors4 and until they are, the best time to do surgery for many individuals will remain unknown.
In summary, while this excellent study clearly makes an important contribution by pointing out the safety and efficacy of early ACL reconstruction when performed as described, its results should not be extrapolated without caution to support a dogmatic position on early surgery for every case.
1. Smith TO, Davies L, Hing CB. Early versus delayed surgery for anterior cruciate ligament reconstruction: a systematic review and meta-analysis. Knee Surg Sports Traumatol Arthrosc 2010;18:304-11.
2. Hospodar SJ, Miller MD. Controversies in ACL reconstruction: bone-patellar tendon-bone anterior cruciate ligament reconstruction remains the gold standard. Sports Med Arthrosc 2009;17:242-6.
3. Andersson D, Samuelsson K, Karlsson J. Treatment of anterior cruciate ligament injuries with special reference to surgical technique and rehabilitation: an assessment of randomized controlled trials. Arthroscopy 2009;25:653-85.
4. Ekdahl M, Wang JH, Ronga M, Fu FH. Graft healing in anterior cruciate ligament reconstruction. Knee Surg Sports Traumatol Arthrosc 2008;16:935-47.
Health Sciences Centre, Department of Surgery, Calgary University, Calgary, Alberta, Canada