Arch Orthop Traumat Surg 93, 207 210 (1979)
Archives of Orthopaedic and Traumatic Surgery ©J F Bergmann Verlag 1979
Behavior of the Extensor Pollicis Longus Tendon in Experiment* K H Wilhelm and L I Qvick Department of Surgery at the University of Munich (Head: Prof Dr G Heberer), Nu 13baumstr 20, D-8000 Munich 2, Federal Republic of Germany
Summary Several experimental rupture tests of the extensor pollicis longus tendon proved that a rupture of a tendon caused by experiment is located in a region in which the rupture is mainly found clinically as well. By using a newly developed Silicon impression system it can be proved that in the course of a tendon there is always a certain place which has the smallest cross section This is more or less identical with the location of the rupture Thus, ruptures of the extensor pollicis longus tendon can be experimentally simulated. Zusammenfassung Das RiBverhalten von 43 Extensorpollicis-longus-Sehnen wurde experimentell untersucht Dazu stand eine erprobte Halteapparatur fir die Sehnen sowie ein verbessertes Abdruckverfahren zur Bestimmung der SehnenquerschnittsflHche zur Verfiigung Aufgrund der auswertbaren Ergebnisse konnte nachgewiesen werden, da B im Verlauf der Extensor-pollicis-longus-Sehne zwischen Daumengrundgelenk und Sehnenfach ein Bereich der geringsten Querschnittsfliche besteht, der iiberwiegend auch in den Ri B miteinbezogen ist Weiterhin findet sich eine eindeutige Abhangigkeit der minimalen Sehnenquerschnittsflache zur Krpergr B 13e, Mittelhandumfang und zur maximalen Belastbarkeit sowie eine Abhangigkeit der maximalen Belastbarkeit zu Krpergr 13 Be und Alter.
The extensor pollicis longus rupture is usually understood as a tear of the tendon distal to the extensor retinaculum This lesion was described by Duplay in 1876 as drummer palsy and in 1896 it was recognized by Diims as a rupture of the tendon. *
Dedicated to Prof Dr A N Witt on his 65th birthday
According to the etiology we can divide these ruptures into four groups: 1 Open traumatic transections where the cause of the lesion is obvious. 2 The subcutaneous rupture secondary to trauma, generally Collesii fractures, wrist strains, fractures of the navicular bone, or severe crushing injuries The rupture does not regularly occur at the time of injury but days, weeks, or months later The pathogenesisis which is thought to be a traumatic injury of the blood vessels within the mesotenon followed by local necrosis of the tendon. 3 Subcutaneous rupture of the tendon due to chronic microtraumas caused by some professional or sporting occupations. 4 Subcutaneous rupture by an underlying disease. Except for the open transection, the pathogenetic theories are based on assumptions and are therefore unsatisfactory It was the question whether it is possible, in an experimental setting, to obtain data which would explain the rupture mechanism of the extensor pollicis longus tendon It is known that ruptures of this tendon occur almost exclusively distal to the extensor retinaculum and within a -in long section where the tendon is led around an osseus hypomochlion. From experimental tests conducted on ruptures of the Achilles tendon we know that the rupture will take place in the area with the smallest cross section and that there are definite dependencies regarding age and stature of the patient He wanted to find out whether there were similar dependencies regarding the extensor pollicis longus tendon We were specially interested in the question of whether the tendon ruptures in this area are only due to its special anatomy or whether other factors were playing a role To find the answers
0344-8444/79/0093/0207/$ 1 00
208
K H Wilhelm and L I Qvick: Behavior of the Extensor Pollicis Longus Tendon in Experiment
to this question we developed a device that enabled us to test different rupture situations The tendon rupture tests were performed at the Department of Material Testing at the Technical University of Munich (Prof Neuber). Experimental Setup A Material In the rupture tests we used only noninjured tendons that were excised within 24 to 36 h post mortem We were sure to expose the tendon from the first metacarpophalangeal (mcp) joint distally to the origin of the tendon at the muscle proximally and then excising the tendon without traumatizing it Until the test was performed the tendons were stored in a cold place being kept moist wrapped in wet linen.
Fig 1 The rupture forms Transverse and oblique rupture with or without longitudinal separation of fascicles
B Testing Equipment The ends of the tendon are attached to an instrument described earlier (Wilhelm, 1973) The free part of the tendon (the distance between the clamps holding the tendon) was 9 cm corresponding to the distance between the first mcp joint and the muscular origin of the tendon The pulling device is built in such a way that the tension on the tendon can be gradually increased until the tendon ruptures The increasing power on the pulling device is measured with an extremely sensitive oscilloscope via a transducer and an amplifier The increasing tension is continuously photographically documented.
C Measuring the Cross Section To be able to measure the cross section at any point of the free part of the tendon we had to use a reproduction system The silicon rubber dough used had the following qualities: 1 Rapid polymerization. 2 Low deformation quotient after polymerization. 3 Constant shrinking quotient. An essential prerequisite for obtaining a good model is the exact mixing of hardener and silicon base The so produced model of the tendon was cut into 2 mm slices which were measured in a precisionstereocomparator (Zeiss) For the calculations we used a PR 440 computer Using more than 20 measuring points, the margin of error is less than 0 1 % with this method In our tests we used 64 measuring points The reproduction of the tendon was made at a fixed tension of 5 kiloponds (kp) For the dynamic rupture tests we used 27 tendons from males and 16 tendons from females.
Fig 2A and B Rupture locations A First mcp joint area B Extensor retinaculum area Most ruptures occur in this area Localization of rupture in rel % of free tension length
B Rupture Locations The experiments showed that it is more accurate to talk about rupture regions rather than rupture spots In our series the tendon ruptured 30 times in the region of the extensor retinaculum, 4 times in the region of the first mcp joint and 9 times between those two (Fig 2). C Tensile Strength
A Type of Rupture The ruptures can be divided into two groups, transverse and oblique ruptures In both groups we found occasional longitudinal separations of tendon fascicles over a distance of up to 6 cm (Fig 1). Frequence of the different rupture types Transverse ruptures Oblique ruptures Rupture (transverse or oblique) with separation of fascicles
8 times 17 times 18 times
The lowest rupturing force was 26 kp and the highest 99 kp The mean rupturing force was 59 1 ± 17 7 kp. D Tendon Cross Section 1 General The photometrically achieved cross section figures were found to have a median value of 7 63 mm 2 for males and 5.82 mm 2 for females The area with the smallest cross section was generally found to be located between the retinaculum and the first mcp joint The mean size of the smallest cross section was 5 44 mm 2 In male tendons this varied between 3 81 and
K H Wilhelm and L I Qvick: Behavior of the Extensor Pollicis Longus Tendon in Experiment
209
l
a: n=27 r = 0713
a:
n=16 r = 0,521
l
Fig 3 Rupture region in relation to the smallest cross section site Localization of rupture region and the smallest cross section (
Fig 5 Maximal tensile strength and smallest cross section, sexrelated Max tensile strength / smallest tendon cross section
) in rel % of free tendon length
years Fig 4 Linear relation between smallest cross section and stature. Smallest tendon cross section / size
Fig 6 Relation between maximum tensile strength and age Max. tensile strength / age
8.46 mm 2 (median 5 96 + 1 49 mm2 ) and in the female tendons between 3 43 and 6 46 mm 2 (median 4 56 + 0 95 mm2 ). 2 Smallest Tendon Cross Section and Rupture Region The relation between smallest cross section and rupture region was examined As shown (Fig 3), there is a high degree of correspondence between those two One can conclude that there is (most commonly) a region with the smallest cross section between the extensor retinaculum and the first mcp joint and that this area most frequently is identical with the rupture site. These facts are analogous to those having been found to be true regarding the Achilles tendon. 3 Smallest Cross Section and Stature There is a statistically significant relation between the smallest cross section and the height of the person (Fig 4) With increasing height, the smallest cross section as well as the mean cross section increases. 4 Smallest Cross Section and Tensile Strength Before as well as after differentiating between a male and a female group there are significant relations between smallest cross section and tensile strength (Fig 5).
1
1
1 1¢
years Fig 7 Relation between maximum tensile strength per smallest cross section (kp/mm 2 ) and age (males) Max tensile strength / cross section in relation to age
210
K H Wilhelm and L I Qvick: Behavior of the Extensor Pollicis Longus Tendon in Experiment
5 Smallest Cross Section and Mid-Hand Circumference Here, too, we have found a statistically significant relation, i e , larger mid-hand circumference is accompanied by a larger cross section. 6 FurtherStatistically SignificantParameters When comparing the tensile strength and age, a significant dependency can be established Tensile strength decreases with increasing age (Fig. 6) The tensile strength also increases significantly with increasing height It is also interesting to note that the cross section decreases with age (Fig 7).
Conclusions Using dynamically increasing tensile force mesuring equipment a statistically significant relation emerges between: 1 Smallest cross section stature. 2 Smallest cross section and mid-hand circumference. 3 Smallest cross section and maximum tensile strength. 4 Maximum tensile strength and stature. 5 Maximum tensile strength and age. Basing on these facts we can state that the rupture of the extensor pollicis longus tendon mainly occurs within the region of the physiological weak spots. Since the clinical ruptures occur in the same region as
those in the test we conclude that it is possible to simulate the rupture of this tendon in the laboratory. This leads to clinical consequences that need to be discussed The hitherto accepted evaluation criteria regarding the rupture of the extensor pollicis longus tendon in the typical area must be queried.
References Arnold, G : Festigkeit und Kraft-Lingeninderungs-Verhalten der Strecksehnen des menschlichen Fu Bes Res Exp Med. 164, 123 (1974) Axhausen, G : Die Spitruptur der Sehne des extensor pollicis longus bei der typischen Radiusfraktur Beitr Klin Chir. 133, 78 (1925) Borsay, J C , Csipak, J , Debre, G : Experimentelle Untersuchungen fiber den Pathomechanismus der spontanen Sehnenrupturen Z Orthop 81, 552 (1952) Briichle, H , Moll, W : Eine Me Banordnung zur Priifung des mechanischen Verhaltens von Sehnen Z Ges Exp Med. 147, 147 (1968) Duplay: Ref Z Orthop Chir 512 (1877) Freilinger, G , Zacherl, H : Zur Ruptur der langen Daumenstrecksehne nach Radiusfraktur Handchirurgie 2, 76 (1970) Kleinschmidt, K : Versuche zur Erklirung der Spitruptur der langen Daumenstrecksehne nach Radiusfraktur Beitr Klin. Chir 146, 530 (1929) K6nn, G : Morphologie der spontanen Sehnenzerrei Bungen und ihre gutachtliche Beurteilung Unfallmed Tagg Landesverb Gewerbl Berufsgenossenschaften 9 (1970) Kdnn, G Everth, H J : Morphologie der spontanen Sehnenzerrei Bungen Hefte Unfallheilk 91, 255 (1967) Moseneder, H , Fink, D , Grabherr, H : Der subcutane RiB der langen Daumenstrecksehne Arch Orthop Unfall-Chir 81, 267 (1975) Nigst, H : Spontaneous rupture of extensor pollicis longus. Reconstr Surg Traumatol 12, 272 (1971) Strandell, G : Subcutaneous rupture of extensor pollicis longus tendon-pathogenesis and treatment, survey based on 208 cases Acta Chir Scand 109, 81 ( 1955) Stucke, K : Sehnenbelastung und -ruptur im Tierversuch. Chirurg 22, 16 (1951) Wilhelm, K : Eine neue Versuchsanordnung zur Belastbarkeitspriifung von Achillessehnen Res Exp Med 160, 80 (1973) Wilhelm, K : Neue Aspekte zur Genese der Achillessehnenruptur Zbl Chir 102, 794 (1977) Witt, A N : Klinik und operative Behandlung der Sehnenzerreil 3ungen Hefte Unfallheilk 91, 262 (1965) Received December 15, 1978
Archives of Orthopaedic and Traumatic Surgery ©J F Bergmann Verlag 1979
Behavior of the Extensor Pollicis Longus Tendon in Experiment* K H Wilhelm and L I Qvick Department of Surgery at the University of Munich (Head: Prof Dr G Heberer), Nu 13baumstr 20, D-8000 Munich 2, Federal Republic of Germany
Summary Several experimental rupture tests of the extensor pollicis longus tendon proved that a rupture of a tendon caused by experiment is located in a region in which the rupture is mainly found clinically as well. By using a newly developed Silicon impression system it can be proved that in the course of a tendon there is always a certain place which has the smallest cross section This is more or less identical with the location of the rupture Thus, ruptures of the extensor pollicis longus tendon can be experimentally simulated. Zusammenfassung Das RiBverhalten von 43 Extensorpollicis-longus-Sehnen wurde experimentell untersucht Dazu stand eine erprobte Halteapparatur fir die Sehnen sowie ein verbessertes Abdruckverfahren zur Bestimmung der SehnenquerschnittsflHche zur Verfiigung Aufgrund der auswertbaren Ergebnisse konnte nachgewiesen werden, da B im Verlauf der Extensor-pollicis-longus-Sehne zwischen Daumengrundgelenk und Sehnenfach ein Bereich der geringsten Querschnittsfliche besteht, der iiberwiegend auch in den Ri B miteinbezogen ist Weiterhin findet sich eine eindeutige Abhangigkeit der minimalen Sehnenquerschnittsflache zur Krpergr B 13e, Mittelhandumfang und zur maximalen Belastbarkeit sowie eine Abhangigkeit der maximalen Belastbarkeit zu Krpergr 13 Be und Alter.
The extensor pollicis longus rupture is usually understood as a tear of the tendon distal to the extensor retinaculum This lesion was described by Duplay in 1876 as drummer palsy and in 1896 it was recognized by Diims as a rupture of the tendon. *
Dedicated to Prof Dr A N Witt on his 65th birthday
According to the etiology we can divide these ruptures into four groups: 1 Open traumatic transections where the cause of the lesion is obvious. 2 The subcutaneous rupture secondary to trauma, generally Collesii fractures, wrist strains, fractures of the navicular bone, or severe crushing injuries The rupture does not regularly occur at the time of injury but days, weeks, or months later The pathogenesisis which is thought to be a traumatic injury of the blood vessels within the mesotenon followed by local necrosis of the tendon. 3 Subcutaneous rupture of the tendon due to chronic microtraumas caused by some professional or sporting occupations. 4 Subcutaneous rupture by an underlying disease. Except for the open transection, the pathogenetic theories are based on assumptions and are therefore unsatisfactory It was the question whether it is possible, in an experimental setting, to obtain data which would explain the rupture mechanism of the extensor pollicis longus tendon It is known that ruptures of this tendon occur almost exclusively distal to the extensor retinaculum and within a -in long section where the tendon is led around an osseus hypomochlion. From experimental tests conducted on ruptures of the Achilles tendon we know that the rupture will take place in the area with the smallest cross section and that there are definite dependencies regarding age and stature of the patient He wanted to find out whether there were similar dependencies regarding the extensor pollicis longus tendon We were specially interested in the question of whether the tendon ruptures in this area are only due to its special anatomy or whether other factors were playing a role To find the answers
0344-8444/79/0093/0207/$ 1 00
208
K H Wilhelm and L I Qvick: Behavior of the Extensor Pollicis Longus Tendon in Experiment
to this question we developed a device that enabled us to test different rupture situations The tendon rupture tests were performed at the Department of Material Testing at the Technical University of Munich (Prof Neuber). Experimental Setup A Material In the rupture tests we used only noninjured tendons that were excised within 24 to 36 h post mortem We were sure to expose the tendon from the first metacarpophalangeal (mcp) joint distally to the origin of the tendon at the muscle proximally and then excising the tendon without traumatizing it Until the test was performed the tendons were stored in a cold place being kept moist wrapped in wet linen.
Fig 1 The rupture forms Transverse and oblique rupture with or without longitudinal separation of fascicles
B Testing Equipment The ends of the tendon are attached to an instrument described earlier (Wilhelm, 1973) The free part of the tendon (the distance between the clamps holding the tendon) was 9 cm corresponding to the distance between the first mcp joint and the muscular origin of the tendon The pulling device is built in such a way that the tension on the tendon can be gradually increased until the tendon ruptures The increasing power on the pulling device is measured with an extremely sensitive oscilloscope via a transducer and an amplifier The increasing tension is continuously photographically documented.
C Measuring the Cross Section To be able to measure the cross section at any point of the free part of the tendon we had to use a reproduction system The silicon rubber dough used had the following qualities: 1 Rapid polymerization. 2 Low deformation quotient after polymerization. 3 Constant shrinking quotient. An essential prerequisite for obtaining a good model is the exact mixing of hardener and silicon base The so produced model of the tendon was cut into 2 mm slices which were measured in a precisionstereocomparator (Zeiss) For the calculations we used a PR 440 computer Using more than 20 measuring points, the margin of error is less than 0 1 % with this method In our tests we used 64 measuring points The reproduction of the tendon was made at a fixed tension of 5 kiloponds (kp) For the dynamic rupture tests we used 27 tendons from males and 16 tendons from females.
Fig 2A and B Rupture locations A First mcp joint area B Extensor retinaculum area Most ruptures occur in this area Localization of rupture in rel % of free tension length
B Rupture Locations The experiments showed that it is more accurate to talk about rupture regions rather than rupture spots In our series the tendon ruptured 30 times in the region of the extensor retinaculum, 4 times in the region of the first mcp joint and 9 times between those two (Fig 2). C Tensile Strength
A Type of Rupture The ruptures can be divided into two groups, transverse and oblique ruptures In both groups we found occasional longitudinal separations of tendon fascicles over a distance of up to 6 cm (Fig 1). Frequence of the different rupture types Transverse ruptures Oblique ruptures Rupture (transverse or oblique) with separation of fascicles
8 times 17 times 18 times
The lowest rupturing force was 26 kp and the highest 99 kp The mean rupturing force was 59 1 ± 17 7 kp. D Tendon Cross Section 1 General The photometrically achieved cross section figures were found to have a median value of 7 63 mm 2 for males and 5.82 mm 2 for females The area with the smallest cross section was generally found to be located between the retinaculum and the first mcp joint The mean size of the smallest cross section was 5 44 mm 2 In male tendons this varied between 3 81 and
K H Wilhelm and L I Qvick: Behavior of the Extensor Pollicis Longus Tendon in Experiment
209
l
a: n=27 r = 0713
a:
n=16 r = 0,521
l
Fig 3 Rupture region in relation to the smallest cross section site Localization of rupture region and the smallest cross section (
Fig 5 Maximal tensile strength and smallest cross section, sexrelated Max tensile strength / smallest tendon cross section
) in rel % of free tendon length
years Fig 4 Linear relation between smallest cross section and stature. Smallest tendon cross section / size
Fig 6 Relation between maximum tensile strength and age Max. tensile strength / age
8.46 mm 2 (median 5 96 + 1 49 mm2 ) and in the female tendons between 3 43 and 6 46 mm 2 (median 4 56 + 0 95 mm2 ). 2 Smallest Tendon Cross Section and Rupture Region The relation between smallest cross section and rupture region was examined As shown (Fig 3), there is a high degree of correspondence between those two One can conclude that there is (most commonly) a region with the smallest cross section between the extensor retinaculum and the first mcp joint and that this area most frequently is identical with the rupture site. These facts are analogous to those having been found to be true regarding the Achilles tendon. 3 Smallest Cross Section and Stature There is a statistically significant relation between the smallest cross section and the height of the person (Fig 4) With increasing height, the smallest cross section as well as the mean cross section increases. 4 Smallest Cross Section and Tensile Strength Before as well as after differentiating between a male and a female group there are significant relations between smallest cross section and tensile strength (Fig 5).
1
1
1 1¢
years Fig 7 Relation between maximum tensile strength per smallest cross section (kp/mm 2 ) and age (males) Max tensile strength / cross section in relation to age
210
K H Wilhelm and L I Qvick: Behavior of the Extensor Pollicis Longus Tendon in Experiment
5 Smallest Cross Section and Mid-Hand Circumference Here, too, we have found a statistically significant relation, i e , larger mid-hand circumference is accompanied by a larger cross section. 6 FurtherStatistically SignificantParameters When comparing the tensile strength and age, a significant dependency can be established Tensile strength decreases with increasing age (Fig. 6) The tensile strength also increases significantly with increasing height It is also interesting to note that the cross section decreases with age (Fig 7).
Conclusions Using dynamically increasing tensile force mesuring equipment a statistically significant relation emerges between: 1 Smallest cross section stature. 2 Smallest cross section and mid-hand circumference. 3 Smallest cross section and maximum tensile strength. 4 Maximum tensile strength and stature. 5 Maximum tensile strength and age. Basing on these facts we can state that the rupture of the extensor pollicis longus tendon mainly occurs within the region of the physiological weak spots. Since the clinical ruptures occur in the same region as
those in the test we conclude that it is possible to simulate the rupture of this tendon in the laboratory. This leads to clinical consequences that need to be discussed The hitherto accepted evaluation criteria regarding the rupture of the extensor pollicis longus tendon in the typical area must be queried.
References Arnold, G : Festigkeit und Kraft-Lingeninderungs-Verhalten der Strecksehnen des menschlichen Fu Bes Res Exp Med. 164, 123 (1974) Axhausen, G : Die Spitruptur der Sehne des extensor pollicis longus bei der typischen Radiusfraktur Beitr Klin Chir. 133, 78 (1925) Borsay, J C , Csipak, J , Debre, G : Experimentelle Untersuchungen fiber den Pathomechanismus der spontanen Sehnenrupturen Z Orthop 81, 552 (1952) Briichle, H , Moll, W : Eine Me Banordnung zur Priifung des mechanischen Verhaltens von Sehnen Z Ges Exp Med. 147, 147 (1968) Duplay: Ref Z Orthop Chir 512 (1877) Freilinger, G , Zacherl, H : Zur Ruptur der langen Daumenstrecksehne nach Radiusfraktur Handchirurgie 2, 76 (1970) Kleinschmidt, K : Versuche zur Erklirung der Spitruptur der langen Daumenstrecksehne nach Radiusfraktur Beitr Klin. Chir 146, 530 (1929) K6nn, G : Morphologie der spontanen Sehnenzerrei Bungen und ihre gutachtliche Beurteilung Unfallmed Tagg Landesverb Gewerbl Berufsgenossenschaften 9 (1970) Kdnn, G Everth, H J : Morphologie der spontanen Sehnenzerrei Bungen Hefte Unfallheilk 91, 255 (1967) Moseneder, H , Fink, D , Grabherr, H : Der subcutane RiB der langen Daumenstrecksehne Arch Orthop Unfall-Chir 81, 267 (1975) Nigst, H : Spontaneous rupture of extensor pollicis longus. Reconstr Surg Traumatol 12, 272 (1971) Strandell, G : Subcutaneous rupture of extensor pollicis longus tendon-pathogenesis and treatment, survey based on 208 cases Acta Chir Scand 109, 81 ( 1955) Stucke, K : Sehnenbelastung und -ruptur im Tierversuch. Chirurg 22, 16 (1951) Wilhelm, K : Eine neue Versuchsanordnung zur Belastbarkeitspriifung von Achillessehnen Res Exp Med 160, 80 (1973) Wilhelm, K : Neue Aspekte zur Genese der Achillessehnenruptur Zbl Chir 102, 794 (1977) Witt, A N : Klinik und operative Behandlung der Sehnenzerreil 3ungen Hefte Unfallheilk 91, 262 (1965) Received December 15, 1978
