ACL Rupture : From Surgery to Return to Sport
- 19 gen
- Tempo di lettura: 5 min
Table of content:
INTRODUCTION
Rupture of the Anterior Cruciate Ligament (ACL) is one of the most common injuries in sports that involve rapid changes of direction, jumping, and landing, such as football, basketball, skiing, or volleyball.
The ACL is located at the center of the knee joint and plays a key role in stabilizing the anteroposterior and rotational movement of the tibia relative to the femur.
When the ligament ruptures, the knee loses stability and limits safe participation in high-impact sports.. Treatment may be either conservative or surgical; however, in athletes and physically active individuals, surgical reconstruction is often the recommended option.
MOST COMMON SURGICAL TECHNIQUES
ACL reconstruction involves the use of a graft to replace the injured ligament. The main surgical techniques include:
Patellar Tendon (BTB – Bone–Tendon–Bone): The central portion of the patellar tendon is harvested together with two bone plugs.
Quadriceps Tendon: A portion of the quadriceps tendon is used, with or without an associated bone fragment.
Hamstring Tendons (Semitendinosus and Gracilis – DIDT): The semitendinosus and gracilis tendons are harvested and combined to form the new ligament.
POST-OPERATIVE PHASE
The phase immediately following surgery is the most delicate, as correct execution of the prescribed exercise program from the very beginning—together with strict adherence to the surgeon’s instructions—can have a decisive impact on the quality of recovery.
Crutches: approximately 4 weeks, with partial weight-bearing allowed immediately if there are no associated meniscal injuries. Partial loading of the operated limb promotes blood circulation, helping to limit muscle atrophy, which is in any case unavoidable during the initial recovery period.
Ice and elevation: essential for reducing pain and swelling.
Possible bruising (hematomas): common in the early post-operative phase.
Early exercises and physiotherapy: the primary goal of the first recovery stage is to reactivate the quadriceps muscle, which rapidly loses tone due to swelling and the relative immobilization required during the first weeks of recovery.
Isometric quadriceps contractions (called also “flash contractions”) are essential during the early post-operative weeks. It is crucial to begin physiotherapy as early as the second day after surgery to initiate joint mobilization—fundamental for restoring a normal range of motion in both extension and flexion—and, when appropriate, to use neuromuscular electrical stimulation to facilitate quadriceps activation (example in the video below).
Situation at 2 Weeks Post-Surgery (after suture and stitch removal): Marked swelling is still present.
At 1 Month Post-Surgery: A marked loss of muscle mass is clearly evident.
FOLLOW-UP AND RECOVERY PROGRESSION
All post-operative follow-up visits with the surgeon aim to assess knee flexion and extension. During this early phase of rehabilitation, the primary focus is to restore as much range of motion as possible as quickly as possible.
Starting from the second month, exercises such as bodyweight half-squats, manually assisted leg curls (in which the healthy leg provides controlled resistance to the operated leg), and glute-activation exercises are introduced. At this stage, it should already be possible to begin using a stationary bike.
From the third month onward, light running is generally introduced, alternating short bouts of running with periods of rest in a 1:1 ratio (e.g., 2 minutes of running followed by 2 minutes of walking). If no swelling or pain occurs after training, the training volume can be gradually increased week by week.
At this point, true strength training and light plyometric exercises can be incorporated. Squats, Romanian deadlifts, hip thrusts, leg press, leg curls, box jumps, and box hops form the core of the program, with the aim of re-gaining the muscle mass and strength lost and improving proprioception.
Linear running or cycling is allowed, while changes of direction and complex jumping movements should still be avoided.
Progressive strengthening in closed kinetic chain exercises (squats, lunges, Romanian deadlifts) is emphasized.
Situation at 6 Months Post-Surgery: Swelling has resolved, the quadriceps appears more toned, and the muscle asymmetry between the two limbs begins to fade. While muscle mass is not a decisive factor for return to play, monitoring it can be useful to assess rehabilitation progression, as greater muscle mass generally translates into a higher capacity to produce force. Strength, which depends on force production, remains the primary indicator when evaluating an athlete’s readiness to return to sport.
Once the 6-month milestone has been reached, the first isokinetic test is performed to assess maximal and explosive strength of both limbs, in both concentric and eccentric phases. At this stage, the strength deficit compared to the healthy limb should generally not exceed −15% to −20%.
In addition to the isokinetic assessment, the sports medicine physician will:
Evaluate any remaining extension and flexion deficits of the operated knee.
Measure thigh circumference to obtain a comparative reference with the healthy limb.
Perform functional tests such as single-leg stance, double-leg and single-leg jumps (single hop and triple hop tests) to assess the level of proprioception.
If the test results are positive and the strength deficit between the operated and non-operated limb falls within the expected ranges, a return to training involving pivoting movements and changes of direction can be considered starting from the seventh month.
Between the eighth and ninth month, a second isokinetic test is performed as a final evaluation to obtain medical clearance for returning to team training and beginning sport-specific reconditioning. This phase includes a gradual return to unrestricted sport activity, involving changes of direction, sprinting, and contact situations.
Example of baseline isokinetic test results:
As mentioned previously, strength values are measured in both limbs for knee extension (quadriceps) and knee flexion (hamstrings), assessing both maximal strength and explosive strength, while ensuring that the difference between the healthy and the operated limb remains within the recommended limits.
In my case, at 8 months post-surgery, I still showed a 13% deficit in maximal strength of the right quadriceps. The difficulty in pushing decisively was not due solely to physical factors, but also to a psychological component—because rehabilitation is not only about muscles: the mind plays a fundamental role. In contrast, for the hamstrings, the deficit was 10%, which falls within the range considered acceptable.
Regarding explosive strength, the deficits were minimal (6% in the quadriceps and 3% in the hamstrings, respectively).
After normalizing strength values to my body weight—a more realistic indicator of performance—both knee extensors and flexors were close to, or even slightly above, normative values, indicating that the remaining gap to be bridged was almost negligible.
Finally, in more field-based tests, I showed a 6% difference between the two limbs in both the Single Hop Test and the Triple Hop Test.
GUIDELINES FOR RETURN TO PLAY
Returning to sport before 9 months significantly increases the risk of re-injury or graft rupture (Grindem et al., 2016).
A strength deficit greater than 10% between the operated and non-operated limb at the time of return to sport is associated with a higher incidence of subsequent injuries (Kyritsis et al., 2016).
Full recovery of proprioception is just as crucial as strength restoration in reducing the risk of recurrence.
CONCLUSION
ACL reconstruction represents only the first step of the recovery process; true success is measured by the quality of rehabilitation and the management of the return-to-sport phase. A gradual approach, guided by objective testing and medical supervision, is essential to ensure a safe return to play while minimizing the risk of new injuries.
Equally important to physical recovery is the mental recovery of the athlete. Regaining confidence in one’s body, overcoming the fear of moving freely, and once again performing sport-specific movements with confidence are fundamental components of a complete and lasting return to sport. Without this balance between body and mind, even a technically perfect muscular rehabilitation may fail to translate into optimal on-field performance.
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