Gender may be a factor in how patients respond after anterior cruciate ligament (ACL) surgery. But there are other important factors at play here. Age, level of strength and activity, and body weight can make a difference. Younger age, higher level of function, and body mass index (BMI) close to normal are all helpful in getting a positive result. For example, if your wife is younger and more athletically active before surgery, these factors could help explain the difference.
Time between injury and date of surgery is also important. You mentioned your surgeries were only two weeks apart, but how long between the dates of injuries? Longer delays can turn an acute injury into a chronic one with more damage to the soft tissues and cartilage and greater instability. Recovery is also more complicated with longer delays.
And remember, people do recover after surgery and progress through rehab at different rates. Hopefully, things will smooth out and you’ll both have good long-term results.