Foundational And Clinical Study For Thumb Extension By Transferring Extensor Carpi Radialis Brevis To Extensor Pollicis Longus

Objective: To study the anatomical foundation and clinical application of reconstruction thumb extendsion by tranferring extensor carpi radialis brevis(ECRB) to extensor pollicis longus (EPL).Methods: Through the anatomical study of ECRB and EPL in 16 fresh adult cadaver's forearms, we set up anatomical model by ERCB tendon transferring to EPL tendon. Observation the anatomical parameter of ERCB and EPL, the courser of ERCB tendon after transferred to EPL, and the extension range of thumb. And we have carried out reconstruction operation on 3 cases of dysfunction of thumb extension by ECRB tendon transferring to EPL in the 3rd hospital of Jilin University from Mar 2006 to Dec 2007.Results:All the specimen of ERCB and EPL observed in enthesis and courser are non-varation. We measure the anatomical parameter of ERCB and EPL respectively as following, the length of venter musculi: 15.5±1.4(12.5-17.0) cm,12.5±1.0(10.8-14.0)cm; the maximal perimeter of venter musculi: 8.5±0.8(7.8-9.5)cm,3.6±0.3(2.8-4.0)cm, the two ratio is 2.36, and calculating the ratio of maximal cross section area is 5.57; the length of tendon: 11.5±1.1(9.8-13.0) cm,13.5±0.7(12.0-14.5)cm; the width of tendon in splicing level: 0.80±0.10(0.70-0.90)cm,0.40±0.10(0.30- 0.60)cm,the two ratio is 2.0; the thickness of tendon: 0.20±0.04 (0.14-0.25)cm,0.10±0.02(0.05-0.15)cm,the two ratio is 2.0,and calculating the ratio of cross section area in splicing level is 4.0. We measure the turning angle of EPL in trochlea on the ERCB transfer model is 30±12°, less 15±8°than that of EPL (45±15°) before ERCB transfer; the included angle between EPL and radius axis via trochlea on the ERCB transfer model is 30±7°, less 20±5°than that of EPL (50±9°) before ERCB transfer. We carry out the thumb extension assessment on the ERCB transfer model, measuring the extension angle of thumb paratelum deviating from index finger is 58±16°, less 8±3°than that of EPL extension(50±12°)before ERCB transfer; dorsal extension angle between the first metacarpal bone and palmar surface is 12±5°,less 3±2°than that of EPL extension(15±8°)before ERCB transfer; the vertical high of thumb tip dorsal extension is 2.3±0.9cm, less 1.2±0.6cm than that of EPL extension(3.5±1.2cm)before ERCB transfer. 3 cases are carried out by ECRB tendon transferring to EPL tendon reconstruction thumb extension in clinical application, and afte a short period follow-up post-operation, the thumb motorfunction of all the cases are achieved above 75% camparing with uninjured side, graded as excellent and good according to the TAM system assessment, the myodynamia recovery of EPL achieves M4, the function of wrist extention has no obviously handicap comparing with pre-operation.Conclusions : Reconstruction thumb extension by ERCB transferring to EPL fits anatomical and biomechanical rules,and has simple procedure , tiny side effect , satisfactory therapeutic effect in clinical application.