Injections: Hydro-Distention
Hydro-distention refers to the mechanical benefit of injecting a joint capsule with an increased volume of fluid.
Overview of Hydro-Distention
What is Hydro-distention
Hydro-Distention is a term relating to 'expansion / distention' of tissues by injecting fluid (hydro).
Why does this help
When joints or tendon sheaths become inflamed they can also develop adhesion's (tissues stick together) which restrict normal movement.
By accurately injecting fluid into the capsule, the capsule is forced to expand (distention).
This distention helps break small adhesion's and stretches the capsule to allow an improved freedom of movement.
Do they work
The mechanical principle is quite simple and logical, but outcomes vary. When fluid (typically saline 'salt' solution) is administered, if the capsule is intact, then the pressure will force expansion.
If however the capsule has a weak area, then the fluid can leak and there is no build up of pressure and consequently only minimal capsule expansion.
All injections offer some degree of distention. In small joints the distention occurs when steroids and local anaesthetic are administered. In large joints, in particular the shoulder joint, additional fluid needs to be added to gain distention.
All injections at the Injection-Clinic are guided
Guided injections ensure the fluid is administered into the target tissue. Hydro-distention simply does not work unless the needle is placed within the capsule.
When to use hydro-Distention
A key pathology for considering Hydro-distention is 'Frozen Shoulder'. The results of Hydro-distention in this condition are favourable and can improve joint range of movement by 25-50%.
Other indications include the paratenon and tendon sheaths. With chronic Achilles tendinopathy, for example, saline solution can be safely administered between the paratenon and the tendon. This helps to breakdown any fibrous and vascular cross links and helps facilitate better freedom of movement.
By forcing a separation between the layers of any tissue, the movement of one tissue over / through another is improved. An analogy is that of a bicycle brake cable that is stiff to move within its outer casing. By creating a separation between the inner and outer cables movement is restored / improved.
Side effects
There are no drug reported side effects with Hydro-distention as the injection solution is typically saline, which is not a medication and therefore has no chemical reaction.
Side effects can however occur in the form of mechanical stretch and resultant pain and soreness.
NOTE: sometimes the Hydro-distention is administered in conjunction with cortico-steroids and therefore in this instance all side effects related to cortico-steroids are relevant.
How long do they last?
The principle of Hydro-distention is to regain normal movement. What can not b e accounted for is the potential of a continuing inflammatory process.
For example, Hydro-distention frees the joint capsule, but the continued active inflammatory process then re-stiffness the joint tissues. This is an unknown variable and therefore no reliable predictions can be made. It is a case of wait and see.
How much do they cost?
The price of a guided Hydro-distention injection is £75.
If the injection is administered with a cortico-steroid then an additional fee of £80 is charged.
All injections are administered to either new or follow up patients. These appointments are £90 and £60.
Typical example for a frozen shoulder is an initial steroid injection. New patient and steroid £90 + £80 = £170.
Then 2 weeks later a hydro-distention injection as a follow up appointment £60 + £75 = £135.
Total cost for a new patient with complete care package for frozen shoulder would be £170 + £135 = £305
