Functional properties of spastic muscles and isolated muscle fibers

Surgery of the upper extremity in cerebral palsy is aimed at improving the
range of motion of the affected joints and, if present, the correction of joint
instability. However, the result of treatment varies and the functional outcome
for the patient is unpredictable. A variety of procedures is available and
during surgery a surgeon is confronted with dilemmas concerning what muscle to
transfer, how the muscle should be mobilized, which route it should take, and
at what tension it should be inserted, considering the individual needs of the
patient. There is not an evidence-based answer to, nor consensus on any of
these questions. Knowledge of the biomechanics of tendon transfer and on the
behavior of spastic muscle is imperative for appropriate surgical planning to
meet the requirements of an optimal muscle balance, and to optimize treatment.
Little is known of the mechanical properties of spastic muscles and there is
discussion as to whetherspastic muscles differ from healthy ones
Previous study has shown that the intra-, inter-, en extramuscular connective
tissue may be of functional significance. There is an indication that the
connective tissues within spastic muscles is different from that of healthy
ones.

To what extent does the resistance to stretch of spastic muscles differ from
that of non-spastic ones?
Does tendon transfer affect a muscle*s functional capacity?

1. harvesting of intra-operatively obtained muscle biopsies of both spastic
(n=20) and healthy (n=20) human FCU (3mm X 5 mm), at the AMC. The biopsies are
coded, subsequently kept, and stored in a relax-solution containing 50%
glycerine.
Mechanical testing of isometric passive and active length-force characteristics
of both isolated muscle fibers with and without their thin layer of directly
adjacent connective tissue matrix (endomysium) and small bundles of muscle
fibers including endo-, and the connective tissue that surrounds the bundle of
muscle fibers (perimysium) of the biopsies, directly after stretch, after 4
minutes at a kept length, and at relaxation to a standardized length.

2. Of the spastic FCU only, active and passive length-force characteristics are
measured during several stages of surgery.

The burden and risks for the patients are small; In the spastic muscle group
the operation will take 30 minutes longer because of the intraoperative
measurements of length-force characteristics by percuteneous electrical
stimulation of the ulnar nerve, while the patient is anaestetized.
Of both groups of patients, a small biopsy is taken (3 mm by 5 mm) of the most
distal part of the flexor carpi ulnaris muscle. Risks are minimal.