An Anterior Cruciate Ligament (ACL) reconstruction is performed predominantly arthroscopically with a small 2 – 3cm incision used for harvesting of the new ACL graft, usually from the medial hamstrings, occasionally from the patella tendon or elsewhere. The initial rehabilitation is primarily influenced by whether there is a meniscal repair performed at the same time as the ACL reconstruction, in which case patients need to use crutches and a range of motion (ROM) brace for 6 weeks.
The total time for rehabilitation is usually 6 – 7 months before returning to sport regardless of whether a meniscal repair was performed or not. The ACL graft once inserted is initially up to 6 times stronger than the normal ACL but as it changes from being a tendon to a ligament, whilst developing its own blood supply, it becomes significantly weaker. At the 6 – 10 week mark, the graft is only 20% as strong as the normal ACL and is at risk for graft stretching or rupture and must be protected during this “at risk” period by restricting your activities to “closed chain drills” for the first 3 months, which basically means your foot must be on solid ground or a stable platform at all times. After the 3 month period, if you have adequate strength and range of motion, a strengthening program will be commenced which can include leg weights and other “open chain” activities.
After achieving reasonable strength within the knee, a conditioning phase is commenced with a graduated return to unidirectional (straight line) jogging and running, usually for a 4 – 6 week period. Once patients are able to run for 25 – 30 minutes in a straight line and have achieved a reasonable fitness base and lower limb strength, then multi directional drills will be commenced and this is one of the most critical phases of the rehabilitation pathway. The original ACL prior to rupture provided position sense (proprioception) which allowed confidence when changing direction or walking on uneven ground. Whilst the new ACL will provide good stability to the knee, it does not develop the proprioceptive nerve fibres that gave the knee position sense and in order to become confident with change in direction activities, these nerve fibres need to be recruited from other knee structures and this is achieved through a series of balance and proprioception drills which include running in a cylindrical and figure of 8 pattern in both clockwise and counter clockwise direction, at initially slow, followed by medium and finally fast pace. The final phase of rehabilitation is sports specific drills as dictated by the relevant sport activity.