ELISABET HAGERT, SWEEDEN
– Interview by Jonny K Andersson M.D., Ph.D., Sweden
Could you explain how proprioceptive training works in theory?
Proprioception is our “sixth sense”, which governs our perception of our own body, both consciously and unconsciously. To train proprioception is to train aspects such as balance, motor control, and the perception of joint position and motion1. Proprioception training is usually targeted to a specific area of concern or a part of the body that needs to be strengthened, for instance in pre-season balance plate training in soccer players to prevent knee and ankle injuries during the competitive season.
Where are the mechanoreceptors located in the Wrist and the Thumb base joints, and what types are most commonly found?
Mechanoreceptors are sensory end-organs sending proprioception information from muscles, joints and skin to both the spinal cord and the brain for afferent information on body position and motion. (Figure 1)
Extensive studies have now been made into the presence and types of mechanoreceptors in the hand and wrist. In the wrist, an abundance of receptors is found in the scapholunate ligament, the dorsal wrist ligaments and the radioulnar ligaments of the TFCC2. The volar wrist ligaments have little to no receptors. In the basal thumb, it is similarly the dorsal ligaments that have a rich mechanoreceptor innervation whereas the volar ligaments are poorly innervated3.
The most common mechanoreceptor types found in the wrist and basal thumb joints are the free nerve endings, signalling pain, and the Ruffini receptors, constantly sending information on joint position and motion.
Which ligaments are the most important in terms of this neuromuscular feedback and Which muscles Could be used in gaining dynamic stability?
Complex question! There are numerous ligaments that have an important function in providing both static stability and sensory information.
In the wrist, one of the most important ligaments is the scapholunate ligament complex, where injuries unfortunately are common in athletes. This ligament complex has an abundance of mechanoreceptors and EMG studies have shown that stimulation of the ligament results in changes in forearm muscle function. Based on these findings, it is recommended that patients with scapholunate ligament tears should be rehabilitated with a proprioceptive training program limiting wrist ulnar deviation (extensor carpi ulnaris muscle function) and instead strengthening the muscles providing a dart-thrower’s motion of the wrist4.
In the basal thumb joint, EMG and muscle kinematic studies have shown that the first dorsal interosseous and opponens muscles are key muscles to strengthen as they provide important stability of the joint5.
Which patients - in terms of Wrist and Thumb base - Could gain from proprioceptive training in your opinion?
If we focus on athletes, there are several sports that could gain from proprioceptive training! One of the most commonly injured athletes that we see are tennis players. The elite tennis player has such a powerful stroke and perform repetitive rotation and deviation of the wrist, which makes tennis players prone to injury of the important Triangular FibroCartilage Complex (TFCC).
Pre-season training should include strengthening of the muscles stabilizing the distal radioulnar joint (DRUJ), including the extensor carpi ulnaris and pronator quadratus muscles, as well as reflex training – i.e. balance plate exercises for the hand/wrist.
Do you See any risk in starting proprioceptive training soon after acute injuries?
Early training is important in allowing athletes a fast return to their sport, but the training must be guided and progress with consideration to the type of injury that has occurred. We suggest a step-by-step program for wrist proprioception rehabilitation where care is taken to ease pain and oedema following injury, followed by training of conscious proprioception senses, muscular control and, finally, reflex training6.
The risk of progressing too fast in rehabilitation is that the injury may not heal properly and that pain and oedema will increase.
Which incisions and surgical techniques should be abandoned in terms of sparing the chance for additional proprioceptive training in the postoperative rehabilitation phase?
It is important to realize that the nerves innervation the wrist joint capsule are also the nerves providing afferent sensory information from mechanoreceptors. If a joint is denervated, the ability of a receptor to signal proprioceptive information is lost.
The prime example of this is the posterior interosseous nerve (PIN), which provides important innervation to the dorsal wrist capsule and the scapholunate ligament. Traditionally, the PIN has been removed in open wrist surgery. By instead using a proximally based capsular flap, as described by Garcia-Elias and myself, the innervation to the capsule and ligaments is retained7.
Performing wrist arthroscopic procedures is also an important measure to avoid unnecessary denervation in all wrist procedures.
Do you think proprioceptive training Could be useful in between seasons i.e. for goalkeepers who are prone to suffer from Wrist sprains and thumb base injuries during the competitive season?
Goal keepers sustain repetitive strains on the wrist and basal thumb joint and are particularly prone to ligament injuries due to this (so called, repetitive stress injury).
By focusing on proprioceptive training as part of the pre-season training, goal keepers are likely to have better chances of handling the tough competitive season without injuries.
It would be advised to have goal keepers focus on global stability exercises of the wrist and basal thumb joint, as well as training of the unconscious, reflex, proprioception sense. (Figure 2)
How Can we in the future prove the effect of these theories?
If we look at the effect of proprioception training on athletes, for instance goal keepers or tennis players, it would be of interest to do a randomized study looking at the effect of pre-season proprioception training and injury patterns/frequence, comparing athletes that receive targeted proprioception training for their hand/wrist, as compared to athletes that have no additional proprioception exercises as part of their overall training routine.
Further studies on the presence of ligamento-muscular reflexes are also needed, to look at the presence of reflex-loops that exist between ligaments/joints and the muscles controlling that joint.
Proprioception research has been done on the knee and ankle joints for several decades, but the studies on the hand and wrist are still fairly recent and there is much that still needs to be done to further our knowledge in this field.
Elisabet Hagert M.D., Ph.D.
Jonny K Andersson M.D., Ph.D.
1. Hagert E. Proprioception of the Wrist Joint: A Review of Current Concepts and Possible Implications on the Rehabilitation of the Wrist. J Hand Ther 2010;23:2-17.
2. Hagert E, Garcia-Elias M, Forsgren S, et al. Immunohistochemical Analysis of Wrist Ligament Innervation in Relation to Their Structural Composition. Journal of Hand Surgery 2007;32:30-36.
3. Mobargha N, Ludwig C, Ladd AL, et al. Ultrastructure and innervation of thumb carpometacarpal ligaments in surgical patients with osteoarthritis. Clin Orthop Relat Res 2014;472:1146-1154.
4. Hagert E, Persson JKE, Werner M, et al. Evidence of Wrist Proprioceptive Reflexes Elicited After Stimulation of the Scapholunate Interosseous Ligament. Journal of Hand Surgery 2009;34:642-651.
5. Mobargha N, Rein S, Hagert E. Ligamento-Muscular Reflex Patterns Following Stimulation of a Thumb Carpometacarpal Ligament: An Electromyographic Study. J Hand Surg Am 2019;44:248 e241-248 e249.
6. Hagert E, Karagiannopoulos C, Rein S, Proprioception in Hand Rehabilitation, in Rehabilitation of the Hand and Upper Extremity, T. Skirven, Editor. 2020, Elsevier Publishing. p. 1393-1409.
7. Hagert E, Ferreres A, Garcia-Elias M. Nerve-sparing dorsal and volar approaches to the radiocarpal joint. J Hand Surg Am 2010;35:1070-1074.