Isokinetic evaluation of eighteen male patients submitted to surgical corretion of acute acromioclavicular luxation with a minimum two-year follow-up

Abstracts

Foram estudados 18 pacientes submetidos ao tratamento cirúrgico de luxação acromioclavicular aguda do grau III da classificação de ALLMAN-TOSSY, todos do sexo masculino com idade média de 36 anos, foram avaliados sob o ponto de vista isocinético com tempo de evolução variando de 24 até 127 meses. A avaliação isocinética foi realizada através de um dinamômetro computadorizado marca CYBEX® modelo 6000 na velocidade angular de 60º/segundo e demonstrou resultados significantes no movimento de abdução no plano neutro, com déficit no pico de torque do lado operado, quando comparado com o lado contra-lateral. Quando comparados os ombros com e sem subluxação, os com subluxação demonstraram défcit no trabalho total tanto na adução quanto na abdução no plano neutro.

Articulação acromioclavicular; homens; luxação do ombro; dor do ombro; procedimentos ortopédicos; biomecânica; seguimentos

ARTIGO ORIGINAL

Isokinetic evaluation of eighteen male patients submitted to surgical corretion of acute acromioclavicular luxation with a minimum two-year follow-up

Flavio Almeida Salles^I; Américo Zoppi Filho^II

^IPost-graduate

^IIDoctor and Head Shoulder and Elbow Group

^{Correspondence}

SUMMARY

Eighteen male patients, mean age 36 years, submitted to surgical treatment of ALLMAN-TOSSY grade III acute acromioclavicular luxation were studied. They were isokinetically evaluated during an evolution period ranging from 24 to 127 months. The isokinetic evaluation was carried out with a Cybex^® 6000 computerized dynamometer, at a 60^º/s angular speed, showing significant results in vertical abduction, with a deficit in peak torque in the operated on shoulder as compared to the contralateral side. When the groups with and without subluxation were compared a deficit in total work was observed in the group with subluxation both in adduction and abduction.

Key Words: Acromioclavicular articulation. Men. Shoulder luxation. Pain in the shoulder. Orthopedic procedures. Biomechanics. Follow-up.

INTRODUCTION

The stability of the acromioclavicular articulation is conferred by the articular capsule and by the coracoclavicular ligaments (conoid and trapezoid). Due to its anatomical situation, this joint is frequently subjected to trauma causing loss of its articular integrity.

Totally lesioned stabilizing mechanisms between the acromium and the clavicle characterize the acute acromioclavicular luxation (LACA) which causes important disorders in the shoulder muscular strength and in the subacromial sliding mechanism⁽⁵⁾.

The acute acromioclavicular luxation and its treatment aroused controversy since the most ancient medical reports, as early as Hippocrates in 460 B.C.

Shoulder surgery has shown great advances in several fields. The two main groups of shoulder disorders — the degenerative alterations represented by rupture of the rotating sleeve and the instabilities comprehending luxations and subluxations of the glenohumeral articulation — have treatment protocols without important conceptual differences among several authors. The same is not observed as concerns the acromioclavicular luxation mainly those considered grade III by the Allman-Tossy^(1,15) classification.

We chose the Allman-Tossy classification since sometimes the radiological exam is difficult to interpret due to bad definition of the acromioclavicular articulation and also because it is more comprehensive and easier to interpret. The Allman-Tossy grade III acromioclavicular luxation comprehends Rockwood's⁽¹³⁾ types III, IV, V, VI, which vary as concerns the deviation percentage and the direction of the clavicle distal extremity⁽¹⁴⁾.

Although the medical literature about this subject is extremely rich, no consensus exists whether the best option is the conservative treatment accepting the deformity or the surgical treatment.

Today, notwithstanding several publications about the theme, we notice that few of them report the late results of the adopted treatment. Thus, we must get acquainted with what happens to the operated on shoulders as concerns function and strength of the upper limb.

In our methodology, we used the Cybex® 6000 computerized electromechanical dynamometer to isokinetically evaluate the muscular strength of the operated on limbs as compared to the contralateral side. This is determined through specific isokinetic parameters as peak torque and work.

Although in our opinion the acromioclavicular luxation causes an important alteration not only in the anatomy but also in the biomechanics of the scapular neck and must have its integrity restored through surgery, our study does not intend to resolve the divergencies about which one is the best treatment.

Our objective was to isokinetically evaluate at short and long term the patients submitted to surgical treatment of the Allman-Tossy^(1,15) grade III acromioclavicular luxation with a minimum two-year post-operative follow-up, observing what happens to these patients shoulders as concerns strength.

CASUISTIC AND METHODS

From December 2000 to January 2001, 18 male 25-54 year-old (mean 36 years) patients with previous diagnosis of Allman-Tossi grade III acromioclavicular luxation and submitted to surgical treatment were isokinetically evaluated using the Cyber® 6000 dynamometer. They were post-operatively followed-up from 24-127 (mean 70.1) months. The surgical techniques involved in this study were Vukov⁽¹⁶⁾, Phemister⁽¹¹⁾ plus coracoclavicular ligaments reparation, subcoracoid thread⁽⁸⁾ and Weaver Dunn ⁽¹⁸⁾. The collected data showed a pattern in the post-operative rehabilitation protocol of the patients, who resumed their professional and daily life activities in a period ranging from 60 to 120 days after surgery.

As inclusion criterion none of the patients should present pain or any abnormality in the contralateral shoulder and these shoulders would be considered the control group.

The movements were abduction and adduction of the affected shoulder and then of the contralateral shoulder in the vertical and horizontal plans with four repetitions and angular speed of 60º / second.

The following isokinetic parameters were used: peak or maximum torque representing the highest value found in the full arch movement, measured in Newton x meter (N x m) and total work defined as the product of the applied force and the total distance through which that force is applied, representing the muscular contraction force during the full arch movement, measured in Joules (J).

In the statistical analysis, the Mann Whitney test was used to compare the group of patients which evolved with radiologically diagnosed residual subluxation in the acromioclavicular articulation and the group without subluxation.

RESULTS

The results were the comparison of the affected shoulder with the contralateral shoulder as concerns movement (abduction and adduction), positioning (vertical and horizontal), and isokinetic parameters (peak torque and work); a statistical study was also carried out comparing the results of the isokinetic study among the with and without residual subluxation groups of patients.

The 18 shoulders isokinetic evaluation has shown:

- Deficit in the peak torque of the operated on shoulder abductor muscles in the vertical plan, as compared to the contralateral shoulder (table 1).

- Presence of residual subluxation in the acromioclavicular articulation leading to diminution of the abductor and adductor muscles total work in the vertical plan (table 2).

DISCUSSION

The aim of our study was to determine the patients' evolution after a minimum two-year period as concerns strength of the operated on shoulders. It was not our intention to evaluate and discuss the most appropriate surgical technique to treat the acromioclavicular luxation.

We know that loss of the acromioclavicular joint normal anatomical integrity can affect the scapular suspensory mechanism⁽⁵⁾ causing alterations in the shoulder biomechanics as: muscular fatigue, impact syndrome and acceleration of the degenerative articular alterations⁽⁸⁾.

Considering the facts above, we aimed through the isokinetic evaluation to correlate these facts with possible alterations in the shoulder strength.

We used the computerized electromechanical dynamometer Cybex® 6000 to isokinetically evaluate the patients as concerns strength of the operated on shoulders^(3,12) as compared with the contralateral shoulders that were our control group, thus eliminating the differences in strength between individuals with large differences of age.

Considering that the early methods to evaluate the shoulder functional parameters as tensiometers and manual dynamometers presented limitations as measuring techniques, reproductibility, and mainly lack of objectivity, we found that the isokinetic evaluation is an objective widely known factor to evaluate orthopedic treatments among us.

As the clinical and radiological exams provide data which can differ according to the examiner, the isokinetic evaluation allows the demonstration of objective data and the documentation of the shoulder movements dynamic analysis, independently of the clinical exam, of the interpretation of the image exams, and many other factors⁽²⁾.

To choose this method, we based ourselves in the Moffroid⁽⁷⁾ and Patton⁽¹⁰⁾ studies which established the first norms for the isokinetic evaluation and underlined the importance of this exam as a reliable and reproductible method for muscular evaluation⁽⁶⁾.

The parameters used to evaluate the shoulder strength were peak torque and total work, represented by numerical and graphic results after the patients effect the movement against an accomodative resistance⁽⁴⁾.

The peak torque is undoubtedly the most mentioned parameter in the literature, easy to determine and defined as the most reliable measurement⁽⁹⁾, representing the maximum value attained during muscular contraction in a certain moment of the movement. This parameter was statistically significant in the abduction movement in the vertical plan (p = 0.049) (table 1). We believe that several clinical factors as pain, atrophy of the muscles and radiographic factors as subluxation and degenerative alterations can be acting in isolation or in association in the genesis of this alteration.

Another determination was total work, a parameter which represents the muscular contraction strength during all the time the movement is being carried out, making more representative the interpretation and evaluation of the results concerning the total functional capacity of the subjects⁽¹⁷⁾. Our casuistic did not show a statistically significant difference for total work in all the movements studied. We believe this is an important result, emphasizing recuperation of these patients' muscular strength after the evolution period that lasted on average 70.1 months.

Also among the evaluated parameters, the relationship between the agonist muscles represented by the abductor muscles and the antagonist by the adductor was included aiming to study the equilibrium between these muscular groups usually demonstrating adductor muscles stronger than the abductor in the shoulder articulation. This pattern was maintained during our study and we did not find statistically significant results in the studied parameters; this shows also rehabilitation of the normal muscular equilibrium.

We have also carried out a comparative study between subjects presenting clavicles without residual subluxation and with residual subluxation (Allam-Tossy). The results were statistically significant for the abduction (p = 0.0314*) (table 2) and adduction (p = 0.0313*) movements (table 3) in the vertical plan; this can be explained by factors as loss of the acromioclavicular articulation congruence associated to alterations in the deltoid and trapezoid muscles insertions that directly interfere in the shoulder biomechanics.

We found statistically significant alterations in the isokinetic evaluation, however we believe that these results are not correlated with the shoulder function in daily life activities (AVD) or with painful conditions, but represents less muscular strength in specific movements of the articulation, since all studied patients did not complain about pain of functional limitation in the AVDs.

In order to reduce the doubts concerning the best option to treat LACA, a study with isokinetic evaluation should be made with patients submitted to the conservative treatment, following the methodology used in this study.

REFERÊNCIAS BIBLIOGRÁFICAS

Trabalho recebido em 22/08/2001. Aprovado em 28/03/2002

*Work performed at the Instituto de Ortopedia e Traumatologia do Hospital das Clínicas - FMUSP.

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Publication Dates

• Publication in this collection
  02 Sept 2005
• Date of issue
  June 2002

History

• Received
  22 Aug 2001
• Accepted
  28 Mar 2002