Flexor tendon injury
The flexor tendons of the fingers connect muscles in the forearm to the joints within the finger to cause them to curl up into the palm. There are two tendons to each finger (superficial and deep) and one to the thumb. In order to hold the tendons into the concavity of the finger as it bends, there is a fibrous sheath, a tunnel, reinforced in sections which act as a pulley mechanism. When tendons are damaged by cutting or disease they easily stick to or jamb in this sheath, and the management of tendon injuries in this area is greatly complicated by the need to preserve this delicate mechanism, and, crucially, the gliding surfaces.
Cut tendons need to be repaired within days of the injury, using techniques which have been developed to allow early movement (to avoid sticking) but with sufficient strength (to avoid rupture during movement). The tendon repairs need to be smooth and not swollen beyond the normal circumference of the tendon. Most surgeons now favour a double repair within the tendon (4 strand) combined with a fine running stitch around the margin of the cut tendon.
If the repair is strong enough, early active movement is vital to maintain excursion of the repaired tendon, and this must be done under the instruction of a hand therapist, with the use of a specially made protective splint. Successful recovery from a cut flexor tendon demands a great deal from the patient in terms of protection of the hand combined with persistent performance of regular controlled exercises, for a period of at least 6 weeks. During this time one false or careless move can cause the repair to come apart. This happens in about 5% of repairs, and if it is recognized a further repair may be successful, but the total period of recovery is extended. Repair of flexor tendons should be seen as a two part process: 1 The repair and, 2 The rehabilitation. These are or equal importance. The principle of rehabilitation is a balance between moving the tendon so that it does not stick, and yet no so forcefully as to cause the repair to come apart.
If the exercise programme is not adhered to, and even sometimes if it is, the tendon(s) may become stuck, leaving limited recovery of movement and function. Tendon injuries are often associated with injuries to other structures such as nerves, blood vessels and bone, and repair of these adds to the complexity of recovery from the tendon injury.
- Flexor tendons glide through smooth tunnels on the front of the fingers
- When these are divided they must be repaired early and expertly
- Rehabilitation/physiotherapy is a specialised process achieving a balance between preserving gliding of the tendon while protecting the repair from rupturing.
- A specialised splint is used to protect the tendon repair.
- The process of healing and therapy extends over a minimum of six weeks and the tendon is not at full strength until 12 weeks.
These periods are shorter in the young.