Botox Clinical Trial

Excessive soft tissue tension (i.e.. tight muscles and associated tissues) is the most limiting factor in lengthening and correction of limb length deficiency. Bone lengthening is achieved by surgically breaking the bone and with the use of an extending device, commonly placed on the outside of the limb, the bones ends are distracted. One millimetre a day is commonly the amount of distraction, however the soft tissue increases in length at a slower pace than the bone which leads to soft tissue tension.

Excessive soft tissue tension leads to:

• Soft tissue contractures temporary or permanent short muscles and tendons
• Joint subluxation or instability joints which slip out of line and are loose
• Pain
• Loss of function inability to move joints properly and difficulty walking This puts the joint in a very vulnerable situation and increases the possibility of subluxation. A similar problem arises during tibial lengthening, when the ankle takes up an equinus position (foot pointing down and in). Both deformities reduce the functional ability of the child and risk the joint becoming permanently damaged.

Increasing pain levels accompany these deformities leading to a greater reluctance to comply with treatment or rehabilitation. The lack of joint mobility has further detrimental effect on the limb as it becomes weak and stiff.

These events become a vicious cycle which is difficult to resolve without further intervention. When soft tissue tension is becoming a problem, i.e. pain levels are increasing and difficult to control, or the joint is under threat of instability, the first course of action is to slow or stop the lengthening for a few days which allows the soft tissue tension to decrease. The drawback with this is the potential for the bone ends to start fusing and prevent further lengthening once the process is resumed. To re start the process means the child has to have a further general anaesthetic to enable the bone to be re osteotomised (re broken).

Online Form 6 Some groups of children who undergo lengthening are more susceptible to soft tissue tension than others and therefore prophylactic surgical measures are employed. In anticipation of the soft tissue tension muscles known to create problems are commonly selected for surgical releases. This has been shown to be an effective method for reducing the effects of the tension but it is not without its problems. Releases done at the time of surgery may heal before the lengthening is complete and may need to be repeated. Releases cause trauma to the muscle or tendon which then heals by scar tissue, a structure known to be less pliable than specialised muscle or tendon tissue. Regaining long term function can be compromised.

Temporarily reducing soft tissue tension during the lengthening phase of treatment which has no long term consequences would be an ideal situation. Botulinum toxin has the ability to do this. Paley (2004) used Botulinum toxin as an adjunct to or in place of soft tissue release during femoral lengthening and noted that it seemed to reduce muscle spasm and pain in patients. Unfortunately this was not supported by any form of evaluative research.