EXERCISES TO IMPROVE TENDON GLIDING
A Physio guide
Tendon excursion can be limited in both a proximal and distal direction. It is therefore important to apply stress to the tendon to aid remodelling of the scar in both these directions. i.e., proximal stress is achieved through active work of the affected tendon, and distal stress through active and passive work of the antagonist tendon. It is therefore more difficult to achieve proximal tendon glide as this is purely limited by the strength and endurance of the muscle whereas distally the tendon can be passively stretched by the therapist or by splinting.
Flexor tendons depend on glide between the tendon and surrounding structures and also between FDS and FDP themselves.
DIP joint flexion, with the PIP stabilised into extension, inactivates FDS and produces gliding of FDP on FDS and it’s surrounding tissues.
PIP joint flexion with stabilisation of the MCPJ in extension encourages gliding of FDS with respect to surrounding tissue (do not let pt. Bend the DIP as this will initiate FDP).
Patients will often present with good FDP pull-through when the finger is blocked in extension, but are poor at making a full fist. It is possible there is not enough force on the tendon adhesion when in extension. Therefore exercise with the MCP and PIP joints flexed to the point where the patient starts to lose DIP motion.
Tendon Gliding Exercises
Hook fist: Maximum glide is achieved between FDS and FDP
Fist position: FDP achieves maximum glide with respect to sheath and bone as well as a fair amount of glide over FDS.
Straight fist: Achieves maximum glide of FDS with respect to flexor sheath and bone.
FPL max. glide is obtained by flexing the IP and MCP joints fully.
Make sure that each of these exercises is preceded by full finger and wrist extension (within the limits dictated by tendon healing of the current stage)
Isolated FDS Exercises
The superficialis tendons have separate muscle bellies which allow isolated PIP flexion of each digit. This is in contrast to FDP to the MF - LF which share a common muscle belly. To achieve isolated FDS activity, flex one finger at a time at the PIPJ, with the uninvolved hand keeping the other fingers in extension.
Extrinsic Flexor Stretching
Distal stretching of the tendon can be accomplished through extrinsic flexor stretching. When wrist and finger extension is equal on both hands it is assumed that full distal tendon excursion has been achieved. If active exercise has not been enough to achieve this, then use passive stretches and splinting.
The structure of extensor tendons are different to those of the flexor and present different challenges! They tend to be thin, broad structures that are very susceptible to scar formation. Over the fingers there is the complex extensor mechanism composed of EDC, interossei, and lumbrical tendons. Adhesions can form anywhere along this system and may limit active and passive finger flexion and active finger extension.
A finger that has full passive extension but lacks active extension is known as an extensor lag. Overcoming this can be difficult bearing in mind that the extrinsic flexors are much stronger than the extrinsic extensors (can only generate 38% of the tension) making the proximal stretching of adhesions a problem.
The type of exercise chosen to improve tendon glide depends on the location of the adhesion. Lack of full extension at the MCP joint indicates an adhesion of the EDC, which is the only extensor of the MCPJ. Types of injuries that lead to these adhesions are fractures of the metacarpals and lacerations over the dorsum of the hand. An extensor lag at the PIP and DIP joints indicates an adhesion of the complex extensor expansion. Adhesions in this area are very difficult to treat.
MCP JOINT EXTENSOR LAGS
Movement of the fingers from a fist to a hook position eliminates the intrinsic muscles, allowing for isolated gliding of the extrinsic finger extensors. If a patient has difficulty in actively maintaining the PIP and DIP joints in flexion, get them to hold a pencil in their flexed fingers, or else tape the fingers into flexion.
Once the patient can perform these exercises with the wrist in neutral then repeat the exercise in with the wrist in more flexion and extension to produce maximal EDC excursion.
PIP AND DIP JOINT EXTENSOR LAGS
Unlike the flexor system, extension of the PIP and DIP joints depends on the combined action of the extrinsic and intrinsic muscles (EDC, lumbrical and interossei). The lumbrical is the main extensor of the IP joints and contracts strongest with the MCP in flexion and IP in extension. Therefore, active PIP and DIP extension should be performed with the MCP joint held in flexion. This position not only encourages intrinsic extension but also directs the force of the extrinsic extensor tendon more distally.
To progress, get the patient to place the palm flat on the table and lift the middle and distal phalanx of the finger off the table. Keep the proximal phalanx on the table by blocking, this ensures that the extensor force is directed toward the distal phalanx, and not MCP hyperextension. If the patient cannot do it in the position, make it slightly easier by placing a pencil under the proximal phalanx.
DIFFERENTIAL EXTENSOR TENDON GLIDE
EDC adhesions are a common problem over the dorsum of the wrist. Differential tendon glide can be restored by alternatively moving each digit into graded flexion, while the adjacent digits are held in extension. Combinations of dynamic flexion and extension splinting can be used to create a shear between these tendons, thus improving differential excursion.
EXTRINSIC EXTENSOR STRETCHING
The way in which extensor tendon adhesions are stretched distally depends on the location of the adhesion. Adhesions distal to the MCPJ are not affected by the position of the wrist. When the adhesion is proximal to the MCPJ, a maximal stretch occurs with simultaneous wrist and finger flexion.
However, do be careful when stretching to achieve full finger flexion. Aggressive efforts may result in increasing an extensor lag. When the restoration of passive flexion occurs at the expense of active extension, the physio should focus on increasing proximal extensor pull-through via active exercise and strengthening, mile minimising aggressive stretching into flexion.
Exercise is the only way that a proximal pull can be exerted onto tendon adhesions. To help with scar remodelling a sustained pull will achieve the best results by encouraging lengthening changes of scar collagen.
Some other examples of exercises to help improve muscle strength and tendon glide are:
· FDS in putty
· Flex PIP against a clothes peg held in the palm
· (if extensor lag present) use a velcro roll to provide graded resistance to finger extensors (use a 12 x 6 board lined with 2 strips of hook velcro, approx. 2” Prt, while a metal can is wrapped with 2 strips of pile velcro approx. 2” apart). To strengthen intrinsic extensors, ask the patient to roll the can along the board by moving the PIP and DIP joints from flexion into extension, while keeping the MP joints straight.
· To strengthen the extrinsic extensors, ask the patient to roll the can by moving the MCP joints from flexion to extension, while keeping the IP joints flexed.