Whilst the discussion from February has not continued, I have been doing
some reading on the role of eccentric overload in the development of
extensor tendinosis. As Scott pointed out, one would need to be sure of
what particular condition is causing a patient's 'tennis elbow'. What I am
putting forward here is a discussion of extensor tendinosis as a cause of
tennis elbow by first describing the pathology, pathomechanics, and
treatment of tendinosis in general, and then relating this specifically to
extensor tendinosis. 

Tendinosis

Pathology: 

The pathology of tendinosis is tendon degeneration without clinical or
histological signs of an inflammatory response (Khan, Cook, Bonar, Harcourt
and Åstrom, 1999). Mechanical overload of a tendon, with inadequate repair,
results in mechanical fatigue and subsequent degeneration (adapted from
Stanley and Tribuzi (1992) p 429; Zuluaga (1995) p 628).

The reliability of studies which have noted inflammation in such
conditions, have been called into question, and tendinosis is generally not
associated with inflammation. Hence the term 'tendinitis' in inappropriate
(Khan, Cook, Bonar, Harcourt and Astrom, 1999).

Presentation 

As per differing grades of overuse injuries: insidious onset, pain after
activity, progressing to pain during, and then to constant pain (Vicenzino,
1995). Area of pain is within a tendon, generally in an area that is
relatively avascular (Williams, 1986). Morning pain and stiffness may also
be noted (Nelen, Martens and Burssens (1989); Williams (1986)).

Associated predisposing dysfunction

In general, tendons are considered to be relatively avascular (Steiner
(1976) cited in Schnatz and Steiner (1993)). A region of relative
avascularity is found in the achilles tendon (between 2 and 6 centimetres
proximal to insertion) (Lagergren & Lindholm, 1958, cited in Williams
1986). This region is also the area of symptoms reported in achilles
tendinosis (Nelen, Martens and Burssens, 1989). However, the above general
supposition lacks supporting studies. Despite this, it is postulated that
the relative avascularity, and slow healing rate, of tendons, combined with
prolonged abnormal repetitive loading, results in the aforementioned
mechanical degeneration (Peacock (1959) cited in Williams (1986); Williams
(1986)).

It has been noted in the literature that eccentric activation of the
musculotendinous unit results in increased forces being produced. Also, an
increased speed of eccentric activation leads to greater force production
in the musculotendinous unit (Walmsley, Pearson and Stymiest, 1986).
Further, eccentric activation results in the series connective tissue
component (including tendon) to be stretched and hence contributing to the
force produced (Wajswelner H and Webb G, 1995). Thus, it can be seen that
eccentric muscular activity preferentially stresses associated tendons.
Following, repetitive eccentric loading to a level to which the tendon
cannot withstand, will result in the aforementioned mechanical degeneration.

Treatment

This targets three main areas: ameliorating the underlying factors
predisposing to the condition (which are those which will lend to
maintenance of the condition and its recurrence); increasing the tensile
capacity of the affected tendon; and symptomatic treatment.

Ameliorating underlying factors:

· Inappropriate movement patterns in aggravating activity: such as in
occupational activities in a patient with elbow extensor tendinosis. 
· Tightness of associated musculotendinous unit: A tight SEC will lead to
greater strain during activity (Stanish, Rubinovich and Curwin, 1986).
Hence tight musculature will result in increased likelihood of tendinosis
in that muscle group. Therefore, stretching is required. Tight quadriceps
has been associated with patellar tendinosis (Curwin and Stanish, 1984, p108).
· Muscular activity imbalances resulting in abnormal stressed in affected
musculotendinous unit: This mainly concerns pelvic muscle imbalances, where
poor pelvic control (eg. overactive TFL and underactive G.med), results in
overactive hamstrings and hence hamstring tendinosis.
· Structural problems: Such as in the foot, where, for example, a rearfoot
varus necessitates greater pronation and hence greater stress through the
achilles tendon.

Increasing the tensile capacity of the affected tendon:

As part of treating tendinosis, it is necessary to improve a tendon's
ability to withstand the eccentric loads placed upon it during the
aggravating activities (Stanish, Rubinovich and Curwin, 1986). Tendon is a
metabolically active tissue that adapts to the stresses placed upon it
(Gerber et al (1960) and Landi et al (1980) cited in Stanish, Rubinovich
and Curwin (1986)). Thus, to preferentially load a tendon, such that it
adapts, eccentric activity must be performed (Wajswelner H and Webb G,
1995). Such exercise can be performed as has been described by Fyfe and
Stanish (1992).

However, it has been cautioned that eccentric training may overload the
tendon (Walmsley, Pearson and Stymiest, 1986). Hence, exercises
prescription would need to be weighed against the severity of a patient's
condition and the patient's functional ability.

Symptomatic treatment:

· Such as: electrotherapy, deloading via taping….



When the above is applied to extensor tendinosis, it can be conceptualised
as follows:

Pathology: mechanical degeneration at the common extensor origin,
approximately one to two centimetres distal to the insertion (where there
is supposedly an area of hypovascularity (Brukner and Khan, 1993, p223
[though a reference was not supplied supporting this]).

Pathomechanics: eccentric overload of the tendon occurs due to poor
movement patterns during occupational activities  / sporting pursuits.
Blackwell and Cole (1994) conducted a biomechanical analysis of novice and
expert tennis players which showed that the novice players tended to use a
backhand technique that lends itself to increased eccentric forces in the
extensor muscles. Similarly, this can be applied to a person who uses
excessive wrist movements in the occupational or home activities.

Treatment: 

- correction of underlying factors: analysis of the aggravating activities
is required to elicit why eccentric overload of the extensor groups is
occurring. Treatment is then targeted at the appropriate areas. Stretching
of the extensor group would also be necessary.
- increasing the tensile capacity of the tendon: a graduated eccentric
exercise programme would be necessary (as per Fyfe and Stanish, 1992). 
- symptomatic treatment: electro, mulligan's mobs…….
- other contributing factors to the patients pain would also need to be
addressed (Cx, bursitis etc)



References


Blackwell JR and Cole KJ (1994): Wrist kinematics differ in expert and
novice tennis players performing the backhand stroke: implications for
tennis elbow. Journal of Biomechanics 27(5):509-16.

Brukner P and Khan K (1993): Clinical Sports Medicine. Sydney: McGraw-Hill
Book Company.

Curwin S and Stanish WD (1984): Tendinitis: its etiology and treatment.
Toronto: D.C. Heath and Company.

Fyfe I and Stanish WD (1992): The use of eccentric training and stretching
in the treatment and prevention of tendon injuries. Clinics in Sports
Medicine 11(3):601-24.

Khan KM, Cook JL, Bonar F, Harcourt P and Åstrom M (1999): Histopathology
of common tendinopathies. Update and implications for clinical management.
Sports Medicine 27(6):393-408.

Nelen G, Martens M and Burssens A (1989): Surgical treatment of chronic
achilles tendinitis. The American Journal of Sports Medicine 17(6):754-9.

Schnatz P and Steiner C (1993): Tennis elbow: a biomechanical and
therapeutic approach. Journal of the American Osteopathic Association
93(7):780-8.

Stanish WD, Rubinovich RM and Curwin S (1986): Eccentric exercise in
chronic tendinitis. Clinical Orthopaedics and Related Research 208:65-8.

Stanley and Tribuzi (1992) Concepts in hand rehabilitation

Vicenzino W (1995): The University of Queensland, Department of
Physiotherapy, Sports Physiotherapy Manual. 

Wajswelner H (1995): The leg. In M Zuluaga, C Briggs, J Carlisle, V
McDonald, J McMeeken, W Nickson, P Oddy and D Wilson (Eds.): Sports
Physiotherapy: Applied science and practice (pp613-42). Melbourne:
Churchill Livingston.

Wajswelner H and Webb G (1995): Therapeutic exercise. In M Zuluaga, C
Briggs, J Carlisle, V McDonald, J McMeeken, W Nickson, P Oddy and D Wilson
(Eds.): Sports Physiotherapy: Applied science and practice (207-21).
Melbourne: Churchill Livingston.

Walmsley, Pearson and Stymiest (1986):  Eccentric wrist extensor
contractions and the force velocity relationship in muscle. The Journal of
Orthopaedic and Sports Physical Therapy 8(6):288-93.

Williams JGP (1986): Achilles tendon lesions in sport. Sports Medicine
3:114-135.




Daniel Belavy
Physiotherapist
Brisbane, Australia



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