ACL Surgery: Impact on Height in Adults and Growing Individuals

Does ACL surgery affect height?

For the vast majority of individuals, especially adults, ACL (Anterior Cruciate Ligament) surgery does not affect a person's final height. However, specific considerations apply to children and adolescents whose growth plates are still open.

Understanding Height and Bone Growth

Human height is primarily determined by genetics, nutrition, and hormonal influences during childhood and adolescence. Longitudinal bone growth occurs at specialized areas called growth plates, or epiphyseal plates, located near the ends of long bones (like those in the legs). These plates are composed of cartilage that gradually ossifies, adding length to the bone.

• Adults vs. Growing Individuals: In adults, typically by the late teens or early twenties, these growth plates fuse and harden, meaning no further increase in bone length is possible. In children and adolescents, the growth plates remain open and are crucial for their skeletal development and ultimate height.
• The Role of Growth Plates: Damage or disruption to an open growth plate can potentially lead to growth arrest, angular deformities, or a limb length discrepancy, which could theoretically impact final height.

ACL Surgery in Adults and Height

The anterior cruciate ligament is located deep within the knee joint, connecting the femur (thigh bone) to the tibia (shin bone). ACL reconstruction surgery involves replacing the torn ligament with a graft, often taken from another tendon in the patient's own body (autograft) or from a donor (allograft).

• Anatomical Location: The knee joint, where the ACL resides, is distal to the major growth plates responsible for leg length in adults. By the time an individual reaches adulthood, their growth plates have already fused.
• Mature Bones: Since the bones are fully mature and no longer growing, the surgical procedure itself, which involves drilling tunnels through the bone to anchor the new ligament, does not interfere with any active growth processes.
• No Direct Impact: Therefore, in adults, ACL surgery has no direct impact on an individual's skeletal height.

Specific Considerations for Pediatric ACL Surgery

While adult ACL surgery carries no height implications, the situation is different and requires careful consideration for children and adolescents who sustain an ACL injury before their growth plates have closed.

• The Risk of Physeal Injury: Traditional ACL reconstruction techniques involve drilling tunnels through the epiphysis (end of the bone) and metaphysis (neck of the bone) to secure the graft. If these tunnels cross or significantly disrupt an open growth plate (physis), there is a potential risk of:
  • Growth arrest: The plate stops growing prematurely.
  • Angular deformity: Uneven growth across the plate leading to bowing or knock-knee.
  • Limb length discrepancy: One leg becomes shorter than the other.
• Growth-Sparing Techniques: Recognizing these risks, pediatric orthopedic surgeons have developed and refined growth-sparing ACL reconstruction techniques. These methods aim to reconstruct the ACL while avoiding or minimizing trauma to the growth plates. Examples include:
  • All-epiphyseal techniques: Tunnels are drilled entirely within the epiphysis, avoiding the physis.
  • Partial transphyseal techniques: Tunnels are angled to cross the physis at a less critical angle or use smaller diameter tunnels.
  • Physeal-sparing techniques: The graft is routed around the growth plates.
• Importance of Specialist Care: For young athletes with open growth plates, it is crucial to consult with a pediatric orthopedic surgeon experienced in these specialized growth-sparing techniques. They can assess the child's skeletal maturity and recommend the most appropriate surgical approach to minimize any risk to future growth.

Potential Indirect or Perceived Effects on Stature

While ACL surgery does not change actual bone length in adults, certain post-surgical factors can sometimes lead to a perceived difference in height or posture. These are generally temporary and addressable with proper rehabilitation.

• Postural Changes: Following surgery, especially during the initial recovery phases, pain, weakness, or a protective gait pattern can lead to altered posture. An individual might subconsciously favor the non-operative leg, leading to subtle shifts in body alignment that could momentarily affect how tall they feel or appear.
• Muscle Imbalances: Prolonged disuse or inadequate rehabilitation can lead to muscle imbalances around the hip, knee, and ankle. These imbalances can affect pelvic alignment or even subtly influence spinal curvature, which might in turn affect perceived standing height.
• Joint Stiffness/Reduced Range of Motion: If full knee extension is not regained after surgery, the leg may remain slightly bent, which could reduce effective leg length and overall perceived height.
• Rehabilitation's Role: A comprehensive and diligent rehabilitation program is essential to restore full range of motion, strength, and proper biomechanics. Addressing these issues through physical therapy helps prevent long-term postural compensations and ensures the individual can stand and move optimally.

Key Takeaways

• Adults: ACL surgery has no impact on final height as growth plates are fused.
• Children/Adolescents: There is a potential, but manageable, risk to growth plates if traditional techniques are used. Modern growth-sparing techniques are designed to mitigate this risk.
• Perceived Height: Temporary postural or gait changes post-surgery can affect perceived height, but these are typically addressed through effective rehabilitation and do not alter skeletal length.

In summary, while the question of ACL surgery affecting height is a valid concern, particularly for younger individuals, advancements in surgical techniques and a thorough understanding of bone growth mean that for most, it is not a factor that will ultimately change their stature.