I rehab far too many athletes under the age of 18 with ACL tears. In many cases, I am rehabbing some who have suffered multiple ACL ruptures before they graduate from high school. The burning question is why do so many clients suffer a graft failure or contralateral injury so so often?

Is it related to genetics? Is sports specialization to blame? Perhaps fatigue and limited recovery is a problem. I think the answer is multifactorial, but to be perfectly honest we as a profession have yet to truly arrive at a consensus as to when the “right time” to return to play is. Opinions vary widely based on the athlete, sport, native movement patterns, graft choice, additional injuries (ligament, cartilage or soft tissue) and the provider.

As a clinician dedicated to both prevention and the best rehab, I am always re-evlauating my own algorithm and rehab techniques, while looking for scientific rationale to direct my exercise selection and decision making processes. A recent paper by Webster and Feller in the November 2016 edition of AJSM looked at subsequent ACL injuries in subjects who underwent their primary ACLR under the age of 20 utilizing a hamstring autograft reconstruction procedure.

In a nutshell, this study’s key points are:

Authors sought to explore the influence of sex and age groupings (<18 years vs 18-19 years at the time of surgery) on the risk of subsequent ACL injury

354 consecutive patients who were younger than 20 years when they underwent their first primary hamstring tendon autograft ACL reconstruction

#of subsequent ACL injuries (graft rupture or a contralateral injury to the native ACL) was determined at a mean follow-up of 5 years (range, 3-10 years)

Subgroup analysis included sex and age (<18 years vs 18-19 years at the time of surgery) comparisons

Graft ruptures occurred in 57 patients (18%) at an average time of 1.8 years after surgery

Almost half (47%) occurred within the first postoperative year, and 74% occurred within the first 2 years

Highest graft rupture rate of 28.3% was in the youngest males (<18 years), and this was significantly higher than in females of the same age (12.9%), as well as in male patients older than 18 years (13.8%)

Contralateral ACL injuries occurred in 56 patients (17.7%) at an average time of 3.7 years after surgery

No significant age- or sex-based differences for contralateral ACL injuries

total number of patients who had at least 1 further ACL injury subsequent to the primary surgery was 110 (35%)

So in essence, here is what we know from this paper:

High re-injury rate was confirmed Early graft ruptures were more prevalent in patients who underwent surgery when they were younger than 18 years versus those in the 18- to 19-year age group Males had higher rate than females with highest risk in the group < 18 y/o

It is important to note this paper was looking at only HS autograft reconstructions. In addition, other studies have found females to be at a higher re-injury risk, so this is yet another grouping of data.

My preferential graft for younger athletes undergoing primary ACLR going back to cutting, pivoting and jumping sports is a patella tendon autograft reconstruction based on years of clinical experience and the faster graft incorporation. There are drawbacks for every graft, and the PT graft offers potential anterior knee pain, extension loss and stiffness, but I believe these factors can be managed with good rehab. The one factor that cannot be controlled is the size of the graft that can be taken and this may be the one consideration to think on.

There is literature to support the use of many types of grafts. It all begins with proper surgery (good placement of the tunnels and graft) followed by good rehab and of course patient compliance. Overall, I feel we are learning more all the time, but future research must address the impacts of neural fatigue (total practice time, recovery, and risk factor of too many games in a short period of time), ideal time frame for return to sport after primary reconstruction, fear of re-injury (kinesiophobia) and the impact of targeted neuromuscular training following a primary reconstruction and its impact on secondary prevention.

Age has been identified as an obvious risk factor for re-injury, but it is also likely that younger athletes are far more likely to resume higher risk sports/activity. Genetics and biomechanics are internal risk factors that must also be considered (family history, alignment, innate movement quality for example) to help guide us in counseling parents, coaches and athletes about future participation and return to play decision making.

Journal Reference: Webster KE, Feller JA. Exploring the High Reinjury Rate in Younger Patients Undergoing Anterior Cruciate Ligament Reconstruction. Am J Sports Med. 2016 Nov;44(11):2827-2832

** Below are some other good reads on this very pertinent subject as we continue to seek the best methods for rehab and injury prevention.

Risk of Secondary Injury in Younger Athletes After ACLR

Reruptures, Reinjuries, and Revisions at a Minimum 2-Year Follow-up: A Randomized Clinical Trial Comparing 3 Graft Types for ACL Reconstruction

Simple decision rules can reduce reinjury risk by 84% after ACL reconstruction: the Delaware-Oslo ACL cohort study