PCL Injuries Are Not ACL Injuries: Why PCL Reconstruction Still Underperforms
A new review explains why PCL reconstruction still underperforms ACL surgery, and what that means for your treatment options.
The PCL is not just an ACL in a different direction in the knee. It is not just the flipped ACL. The PCL is very different in function, strength, importance, and, as it turns out, in how we fix injuries. Most can be treated without surgery with conservative treatment and, when surgery is required, the results are harder to predict. The nerds of orthopedics (of which I am one) are still arguing about how best to do the operation.
A new current concepts review in the Orthopaedic Journal of Sports Medicine (Erden and colleagues, with Robert LaPrade as senior author) lays out why1. It reviewed eight major controversies in PCL reconstruction and reached a conclusion I agree with: success depends less on finding one perfect technique and more on finding and fixing each patient's specific risk factors.
Why the PCL is a tougher ligament to replace
The native PCL is a big, strong ligament, with a cross-sectional area of roughly 88 mm² and a failure load near 1,600 newtons1. None of the grafts we have, autograft or allograft, matches that. A quadriceps tendon graft comes closest at 75 to 85 mm², and in a smaller patient or a multiligament injury it is harder still.
The healing environment is also harsher. After an ACL reconstruction, the graft is not constantly pulled backward. After a PCL reconstruction, gravity pulls the tibia back, hamstring contraction pulls it back, and the graft has to survive that while it is still turning into living ligament. If any of you have had an ACL reconstruction with me, you know I talk a lot about "stressing the ligament before it is ready," so we avoid pivoting and twisting on the knee to avoid that stress. One problem with the PCL is that it is constantly under stress from gravity and the normal pull of our hamstring. So, in some ways, it is nearly impossible to avoid introducing stress to the PCL before it heals.
When PCL reconstruction fails, it is rarely one thing
The authors argue that failures usually come from several problems stacking up on the graft1. They sort them into five groups, shown below. The most common single missed problem is an unrecognized posterolateral corner (PLC) injury, the corner of the knee on the outside that also resists backward and rotational motion. If it is not treated, it overloads the PCL graft. Just like I discuss on my revision ACL page, the need to identify the WHY is critical.
| Failure category | Examples |
|---|---|
| Technical | Tunnel in the wrong place (anterior femoral tunnel is most common), fixation failure, graft abrasion at the killer turn |
| Biologic | Graft not incorporating or healing into ligament |
| Missed associated injury | Posterolateral corner (most common), medial-sided injury, missed ACL tear |
| Alignment | Low posterior tibial slope (under about 8 degrees), bowlegged (varus) alignment |
| Rehabilitation | Early hamstring loading, inadequate bracing, returning to sport too soon |
What is still debated
Single versus double bundle is the classic argument. Lab studies favor double bundle for restoring normal motion, but pooled clinical studies have not shown a clear advantage in patient-reported scores. Transtibial versus tibial inlay is similar: the inlay avoids the killer turn on paper, but studies have not shown a consistent clinical difference. Autograft has a modest edge in single-bundle surgery, and when allograft is used, fresh-frozen is preferred over irradiated tissue1.
Two newer ideas, suture augmentation (the "internal brace") and slope-correcting osteotomy, are still investigational. The authors reserve them for selected high-risk patients, with anatomical risk factors for recurrent injury.
| Question | What the lab shows | What patients show |
|---|---|---|
| Double vs single bundle | Double bundle restores motion better | No clear difference in pooled scores |
| Tibial inlay vs transtibial | Inlay lowers graft stress | No consistent difference |
| Residual looseness | Alters joint contact and loads the cartilage | Often feels fine in the short term |
| Suture augmentation | Shields the graft early | No comparative studies yet |
Rehab is part of the surgery
The review calls rehabilitation the least standardized part of PCL care, and possibly the most important. Because hamstring contraction pulls the tibia backward, most protocols avoid resisted hamstring exercises for at least 12 to 16 weeks, and use closed-chain exercises like leg press and squats instead. The authors also favor dynamic bracing, which pushes the tibia forward, for a prolonged period (at least 6 months) in higher-risk cases1.
Who I talk to about this
I tell patients up front that a PCL tear is not an ACL tear. Mild injuries (grade 1 and 2) in an isolated PCL often do well with structured nonoperative care and bracing, with surgery reserved for those who keep having problems. Higher-grade tears, combined injuries, and revision surgeries are where the details matter most: checking the posterolateral corner, tibial slope and alignment, and planning rehab before the operation, not after.
Frequently asked questions
Can a torn PCL heal without surgery?
Many mild, isolated tears (grade 1 and 2) do well with structured rehab and a brace. Higher-grade tears and combined injuries are less likely to do well without surgery.
Why can't my PCL be fixed like an ACL?
The PCL is bigger and stronger, gravity and hamstrings keep pulling on the graft while it heals, and it is often torn along with other ligaments that also need attention.
Will I get arthritis if my PCL is not fully tight afterward?
Leftover looseness changes how the knee loads the cartilage, particularly the inner side and the kneecap. Many people feel fine for years, but this is one reason we measure looseness and not just how you feel.
Is a double-bundle reconstruction better?
It restores normal motion better in lab studies, but the clinical studies do not show a clear advantage yet. It may make sense in higher-risk patients.
How long will I be in a brace?
It depends on the injury. The authors favor prolonged dynamic bracing in higher-risk cases, but the best duration is not yet settled.
If you have a PCL injury, or you were told you need PCL surgery, come in and we can go through your imaging, your exam, and your options. A frank conversation about what to expect is the best place to start.
References
- Erden T, Tollefson LV, Wilebski BJ, Sawyer ER, Freetly TJ, LaPrade RF. Controversies in PCL reconstruction: why does PCL reconstruction still underperform? Failure mechanisms, residual laxity, and a risk management framework. Orthop J Sports Med. 2026;14(10):23259671261481591. doi:10.1177/23259671261481591
This article is general education, not medical advice for your situation. Every knee and hip is different — talk with your own doctor about your care.