Anterior cruciate ligament (ACL) reconstruction, which involves replacing the damaged ligament with a tissue graft, is a common orthopedic procedure. The success of this surgery is heavily reliant on the patient’s commitment to a disciplined, multi-month recovery process. The new graft is initially held in place by surgical hardware and is at its most vulnerable in the first few weeks, requiring precise protection as it biologically incorporates into the bone. Avoiding certain actions and non-adherence to medical guidelines can lead to complications such as graft failure, permanent loss of mobility, or prolonged recovery time. These guidelines outline missteps to avoid during rehabilitation to protect the knee and ensure a full return to function.
Errors in Immediate Post-Operative Care
Do not neglect the prescribed schedule for icing and elevation, especially in the first few days. Failing to keep the surgical leg elevated above heart level allows excess fluid to pool, leading to significant swelling, or effusion. Uncontrolled swelling causes pain and can inhibit the quadriceps muscle, delaying the crucial early muscle activation required for recovery.
You must not allow the incision site to get wet until your surgeon explicitly clears it, which is typically around ten to fourteen days post-surgery. Soaking the wound in a bath, hot tub, or pool introduces a high risk of bacterial contamination that can lead to a serious joint infection, or septic arthritis. You should immediately contact your medical team if you notice signs of infection:
- A fever above 101°F.
- Excessive spreading redness around the incision.
- Thick, foul-smelling drainage.
Do not abruptly stop or underutilize your prescribed narcotic pain medication. Uncontrolled pain can prevent you from performing the necessary early range-of-motion exercises, which are paramount for preventing long-term stiffness. Use the medication as directed to keep pain levels manageable to facilitate movement. Transitioning to over-the-counter pain relievers should be a gradual process guided by your physician.
Movement and Positioning Mistakes
Do not put full weight on the operative leg before receiving explicit clearance from your surgeon or physical therapist. The new ligament graft is weakest around six to twelve weeks post-surgery as it undergoes a process called ligamentization. Premature full weight-bearing, especially if a meniscal repair was also performed, can lead to excessive tension on the graft, causing it to stretch. This stretching results in permanent knee laxity or bone tunnel widening.
During the early weeks, you must avoid any movement that involves pivoting, twisting, or sharp rotation of the knee joint. These motions introduce rotational forces and shear stress that the still-healing graft cannot withstand, which can result in graft failure. You should also not prop pillows directly underneath the back of the knee while resting or sleeping. This position promotes a bent knee, which can make achieving and maintaining full, straight knee extension (0 degrees) exceptionally difficult, leading to arthrofibrosis.
You should not remove your prescribed knee brace for walking or weight-bearing activities unless instructed to do so by your physical therapist. The brace serves as an external restraint to protect the graft from uncontrolled movements. Similarly, you must not push the knee past the neutral, straight position into hyperextension, especially if you naturally have hypermobile joints. Hyperextension places undue strain on the graft and is a risk factor for graft stretching and rupture, particularly in the first few months.
Mistakes in Rehabilitation Compliance
Do not skip your scheduled physical therapy (PT) appointments, as patient non-compliance is a primary factor in poor long-term outcomes. The physical therapist designs a progressive program to match the biological healing timeline of the graft and safely advances your load-bearing and range-of-motion activities. You must not lie to your therapist about completing your home exercise program or about your pain levels, as this can lead to inappropriate progression of exercises.
Do not push through sharp, intense, or shooting pain during exercises, as this signals a potential issue like graft irritation or hardware impingement. This is distinctly different from the dull, aching muscle soreness that is a normal part of building strength in the recovering quadriceps and hamstring muscles. Sharp pain means stop and report, while general muscle soreness that resolves within a day or two is acceptable.
Do not stop performing the prescribed home exercises once mobility starts to improve. Home exercises are designed to maintain the range of motion and initial strength gains made in therapy sessions. Furthermore, you must avoid aggressive quadriceps strengthening exercises, such as open kinetic chain (OKC) leg extensions with heavy resistance, particularly between 40 and 0 degrees of knee flexion, as this movement causes the highest anterior shear force on the new ACL graft.
Premature Return to Activity and Lifestyle Errors
Do not attempt to drive until you are medically cleared, which includes being off all narcotic pain medication. If the surgery was on your right leg, you must wait until you can confidently perform an emergency stop without pain, which often takes four to six weeks. If the surgery was on your left leg and you drive an automatic vehicle, you may be cleared sooner, as long as you are not taking narcotics that impair reaction time.
Do not attempt to return to high-impact activities too soon, as this leads to a high risk of re-injury. You must not engage in running, jumping, or cutting sports until at least nine to twelve months post-surgery, and only after passing a battery of functional tests. These tests typically include achieving a limb symmetry index (LSI) of at least 90 percent for the injured leg compared to the uninjured leg, particularly in quadriceps strength and hop tests.
Avoid prematurely lifting heavy weights, especially in the lower body, for at least three to six months, as excessive loading can cause hardware failure or delay the graft’s incorporation into the bone tunnels. Finally, do not ignore the psychological component of recovery, such as fear of re-injury. Returning to sport without addressing a lack of confidence in the knee can lead to compensatory movement patterns, which increases the risk of a second ACL injury.