Friday, October 24, 2008

Professor Ulrich Mennen, South Africa, about hand and related injuries

I got an interesting email from Editorial Director Marita Kritzinger. I'll send this posting to her and she can forward it to Professor Ulrich Mennen for approval.

Dear Helge,

Since we last spoke about carpal tunnel syndrome and dentists, I interviewed a South African hand surgeon, Prof Ulrich Mennen, who had some interesting points about the definition of CTS and brings a South African perspective to diagnosis and treatment of it. I’ve attached the article for your interest. If you’d like to publish any of it on your blog, I’ll check with him if he’s ok with that – but I don’t think he would mind.

Kind regards


In your hands

The ability to practice dentistry is reliant on a number of factors, not least the physical presence of your hands. In line with the approach of dental ergonomics, which encourages a deeper awareness and respect for your hands and spine, renowned hand surgeon, Professor Ulrich Mennen (South Africa), talks about the hand and related injuries.

Question: What makes the human hand unique, compared with other animals such as primates?

Ulrich Mennen: The human hand is by far the most developed prehensile organ among all living creatures. The sense of touch in all modalities (light touch, deep touch, pain awareness, proprioception, temperature appreciation, two-point discrimination, stereognosis, vibration) is better developed in the human than in any other mammal. Touch, combined with the highly developed extrinsic and especially the intrinsic muscle function, enables the human hand to perform a wide spectrum of highly sophisticated activities.

This highly developed effector, and at the same time affector, organ further serves to communicate with the surrounding world. Hand language, as part of body language, is a powerful tool for interacting in various ways: it ‘speaks’, it ‘sees’, it ‘hears’, it ‘expresses’, it ‘conveys’ and it ‘receives’. The hand also has a significant emotional dimension which reflects much of ‘me’.

The opposable thumb, unique to humans, preceded the development of the cognitive brain by a few million years. It allows precision and power grips. The combination of the dexterous hand and the brain with its ability of conceptual thought inaugurated modern technology.

Question: What are the most common workplace-related injuries of the hand that you see in your practice?

Ulrich Mennen: It is difficult to single out one or two most common injuries. One sees and deals with all types. Injury, by definition, refers to tissue damage. The cause of an injury may be mechanical, thermal, chemical, electrical, an auto-immune reaction, degenerative lesions, overuse, etc. The body’s response to these insults is always the same: inflammation. Inflammation is the first step towards healing. The aim of wound/tissue healing is to restore structural and functional integrity to damaged tissues. Tissue healing may be divided into three phases: the inflammatory phase, the fibroblastic (proliferative) phase and the scar maturation (remodeling) phase. Treatment should always match the phase of tissue healing as this ensures the most beneficial treatment outcome.

The most severe injuries are caused by a failure to adhere to safety measures as well as (in South Africa) unskilled or untrained workers who handle sophisticated and dangerous equipment e.g. presses, angle grinders.

Question: Do you have any general advice you could give to a person whose profession can make him/her prone to repetitive strain injury, particularly in the arm and hand?

Ulrich Mennen: The concept ‘Repetitive Strain Injury’ should be clarified first.

An article which I published in the South African Orthopaedic Journal in November 2000 setting out the viewpoint of the South African Society for Surgery of the Hand, lists some of the terminology that is used for this so-called condition. The debate about the usage of the term has been raging in industrialized countries, especially Britain, USA and Australia for quite some time.

Our stance in South Africa is:

  • Work related injuries naturally do happen. The clearest form is an injury on duty. These conditions should obviously be prevented and compensated.
  • Certain work activities aggravate symptoms. Any type of activity such as sport, home activities and work could aggravate an underlying condition or disease, which is not necessarily related to the work situation.
  • Most of the aggravated symptoms could be relieved by conservative management, hand therapy and custom-made splints, as well as improvement in the ergonomics of workstations and the work environment. [Helge: I agree]
  • The emphasis should therefore be to prevent the aggravation of symptoms, rather than the compensation of symptoms, which is based on a vague diagnosis.

  • Since prevention involves inspection of workstations and work environment, occupational therapists and especially hand therapists with an occupational therapy background, could do the necessary changes and recommendations. [Helge: I've spoken about this with physiotherapists and they agree based on practical experience]

As an example let us look at the common carpal tunnel syndrome. If the propensity exists for the carpal tunnel to be restricted in size (and there may be many causes for this e.g. gout , previous injury , hormonal changes , rheumatoid arthritis , normal age related wear-and-tear), then any repetitive activity such as typing may cause some swelling , which will result in median nerve compression , in turn causing ischemia (reduced blood flow) which then produces the typical symptomatology. Add to this the unphysiological functional position of wrist flexion while typing, and you have the perfect recipe for median nerve ischemia.

The same person will also develop Carpal Tunnel Syndrome if she were to knit or sleep with her wrists in flexion. Her work has only aggravated the condition. Surely the employer cannot be held responsible for the narrow carpal tunnel. Unfortunately, many interest groups (such as lawyers, trade unions etc) insist that the employers compensate these diseases. In South Africa fortunately we have resisted the demand by these interest groups to label our patients with unscientific diagnoses and subsequently force employers to pay compensation.

Question: What advances in hand surgery and hand therapy make it possible for people suffering from RSI to recover from their injuries and rehabilitate fully.

Ulrich Mennen: It is most important that a firm diagnosis is not made on vague symptoms or signs. Once the patient has been labeled with a diagnosis, it is virtually impossible to get rid of this diagnosis. The diagnosis should be based on firm clear scientific evidence. Furthermore, it is also important not to blame the work situation for an ailment if a direct link cannot be proven, for example such as an acute injury. Having said this, it is well recognized that certain conditions can be aggravated by inappropriate working conditions, and for this reason it is important that a survey should be done of the work situation and ergonomic recommendations be made by a qualified hand therapist with an occupation therapy background. Hand therapy has made huge strides in managing the symptoms and signs of work related disorders. The biomechanical understanding, as well as physiological basis of the tissue response to injury, is much better understood nowadays. Many effective modalities are available to address these conditions. Patients should be referred only to qualified hand therapists and not indiscriminately to ‘physiotherapy’.

Professor Ulrich Mennen has a private hand surgery practice in Pretoria, South Africa. He is head of departments of orthopaedic surgery and hand and micro-surgery at the Medical University of South Africa, MEDUNSA. He is a member of the SA Society for Surgery of the Hand, SA Orthopaedic Association, SA Society for Hand Therapy, SA Assocaition for Occupational Therapy and executive council member of the International Federation of Societies for Surgery of the Hand. His research areas of interest include bone healing and internal fixation, nerve suture (end-to-side-technique), moist wound management and tendon transfer.

Added this by the request of professor Ulrich Mennen:

“Nerve conduction studies may be helpful only in certain cases of nerve compression syndromes eg. Carpal tunnel syndromes. This is because it has been shown that this type of special investigation unfortunately is not very sensitive and can result in false positive or false negative values. We rely more on high definition sonar , which shows the exact area of compression and it can measure the exact diameter of the nerve as well . Furthermore, sonar can be done ‘dynamically’ ie. by flexing muscles through which a nerve passes, or flexing joints eg. the wrist, kinking of the nerve can be observed accurately.”

HELGE: Very interesting! I'd like to add all necessary links and references to this blog posting. What could we at Mediracer do to provide a focused occupational health service to dentists. My understanding is that the high-frequency vibration is one of the causes to "Hand Arm Vibration Syndrome" (HAVS) and carpal tunnel syndrome (CTS). I'd also like to suggest that someone from Mediracer vists you, Marita Kritzinger, to provide an hands-on demonstration of how easy to use the Mediracer is.

Background about Dental Learning Hub: Editorial Director Marita Kritzinger wrote me an email about a group of "crafts people" that have the potential to develop RSI and or CTS. I'd not written about dentists and carpal tunnel syndrome a single time before her email. Now there are several postings about this subject.
Please, send your comments. I'd like to see you folks discussing this posting.

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