Rehabilitation is of major importance in the success of cruciate ligament surgery.
Braces for knee instability
These are used during sports activity where there is a high risk of knee ligament damage, with the aim of protecting the knee from both direct and indirect injury. They may be single-hinged or double-hinged (a hinge on one side of the knee joint only, or a hinge on both the outer and the inner side). The design aim is to prevent excessive anterior or posterior translation (i.e. the thigh bone moving forward or backward relative to the shin bone), excessive rotation (the thigh bone cork-screwing relative to the shin bone), or excessive varus or valgus angulation (being forced into a bow-leg or knock-knee angulation).
There is obviously a great deal of interest by professional athletes in this group of braces, but the literature suggests that there is insufficient evidence of any real efficacy in reducing the incidence or the severity of ligament damage, and some studies have shown increased knee injury in brace wearers, as well as an associated increase in ankle and foot injuries on the same side.
Rehabilitative braces are designed to allow the surgeon to dictate after surgery the degree of motion allowable at the extremes of range in order to decrease the strain on the knee ligaments, particularly the operated one.
Again, however, the literature to date suggests that there is no significant difference between the results in post-operative patients who use such braces and those who do not.
Functional knee braces are designed to minimise external and internal rotation ('foot rotating outwards or inwards') and anterior and posterior translation in patients who have mild to moderate anterior cruciate ligament instability and who are waiting for surgery or who refuse surgery.
Functional knee braces may come 'off-the-shelf' or be custom-fitted. Custom braces are generally advocated for asymmetrically-proportioned legs, high-intensity activities and maximal comfort, while off-the-shelf braces are advocated for patients with minimal symptoms of instability or fluctuating leg circumference (e.g. during rehabilitation).
Both types of brace are generally of similar design and use either a 'hinge-post-shell' (which incorporates moulded shells of plastic and foam connected by lateral hinges - i.e. hinges on the outer side) or 'hinge-post-strap' (which relies on bilateral - i.e. on the outer and inner side - hinged supports attached to leg and thigh straps). The hinge-post-shell design seems to provide enhanced control, durability, rigidity and flesh contact.
Principles of cruciate rehabilitation
What one needs to remember in planning rehabilitation after cruciate ligament surgery is that every single graft used today, whether natural or synthetic, from your own body or someone else's, lacks a blood supply when it is inserted during surgery.
The first period of rehabilitation concentrates on preventing the formation of adhesions (internal scars) inside the knee by passive range-of-motion exercises and efforts to minimise inflammation. While still in bed active work will focuses on keeping strength in the quads muscle as it is so very sensitive to early inhibition. Once up and about initially only gentle active work will be allowed.
As rehabilitation progresses, attention will focus initially on regaining range-of-motion. Strength and endurance training will come later, and there will also be later emphasis on re-educating the leg with balance exercises.
Should return to sport be delayed until two years after anterior cruciate ligament reconstruction? Biological and functional considerations. Nagelli1 CV and Hewett TE. Sports Med. 2017 Feb; 47(2): 221–232.