Regional tendon transfer in massive rotator cuff tears
Authors: L Celli
References: SECEC 2005, Rome
Tendon transfer is a surgical procedure by which a tendon insertion is moved from one location to another.
The muscle-tendon unit is transferred in order to substitute the lost motor function (movement and stability) when repairs of injured muscle is impossible.
Beewood (1976) wrote: “the brain only knows function not individual muscle action”.
In the irreparable rotator cuff tear, good results can be obtained with regional tendon transfer taken from the scapular-thoracic region.
The surgeon for preserving the function of the transferred muscle (static, dynamic, static-dynamic effects) has to understand the biomechanical principles involved and to perform meticulous surgical technique.
The biomechanical purposes
SELECTION OF THE DONOR MUSCLE WITH:
- Appropriate force and work capacity.
The maximum potential force of each contracting muscle is directly proportional to the physiological cross-sectional area of its muscle.
- Strength of the antagonist muscle
Avoid postoperative over correction Bunnell (1948) said “transfer operation=balance operation”.
- The effective amplitude or excursion of the muscle tendon unit
It is directly related to the resting length of its fibres, estimated by the excursion of the tendon that is needed for a given range of motion of the humeral head.
- The synergic muscle contraction
The muscle transferred recovers better function if it has the same phase function of the muscle that must be substituted.
- Mobility of the joint
Tendon transfers should not be performed without acceptable passive mobility of the scapulo humeral joint.
- The sufficient length of the transferred muscle tendon unit
The over tension of the transfer realises: the tenodesis effect the sufferance of the neuro vascular pedicle the risk of secondary rupture of the tendon.
- One tendon crossing two joints in series
When a tendon crosses more than one joint, it always has an effect on each joint in proportion to the moment arm that is has at each axis.
The surgical principles
- The direction of the tendon transfer
As far as possible tendon transfer should pass straight from the origin of the muscle to the new insertion.
- The quantity and quality of the scar tissue
The scar tissue surrounding the tendon transfer reduces the tendon excursion and the strength of the muscle contraction.
- The tendon transfer insertion
The resultant force of the tendon transfer has to recover the active movements and the balance with the resultant forces of the antagonist muscles.