Abstract
Introduction
The rotator cuff muscles help stabilize the glenohumeral joint. Postoperative recovery of rotator cuff muscle strength appears to be an important factor for optimal joint stabilization and the resumption of professional and/or sports activities.
Objective
To study the relationship between internal rotator (IR) and external rotator (ER) muscle strength, shoulder function and the resumption of sports activities (as typically evaluated with functional scores) following surgical stabilization with the Bristow-Latarjet procedure in cases of chronic shoulder instability.
Patients and methods
Twenty patients with anterior, post-traumatic, chronic shoulder instability were included prospectively in a cohort study. The Rowe and Walch-Duplay functional scores were rated for the operated shoulder and the isokinetic IR and ER peak torque values were evaluated with a Con-Trex ® dynamometer before surgery and then 3, 6 and 21 months afterwards. The isokinetic evaluation was performed (at 180°/s, 120°/s and 60°/s) in the seated position, with the arms in 45° of abduction and 30° of antepulsion in the plane of the scapula.
Results
There were no significant postoperative correlations between shoulder function (as judged by the Rowe and Walch-Duplay scores) and IR or ER muscle strength.
Conclusion
This study did not provide evidence for a correlation between IR and ER muscle strength and functional scores after surgical stabilization of the shoulder. However, it is necessary to objectively measure the rotator cuff strength recovery to adequate the strengthening of rotator muscle prior to the resumption of sports activities. Isokinetic strength assessment may thus be a valuable decision support tool for the resumption of sports activities and would complement the functional scores studied here.
Résumé
Introduction
Les muscles de la coiffe des rotateurs de l’épaule ont un rôle dans la stabilisation de l’articulation glénohumérale. La récupération de leur force musculaire après une stabilisation chirurgicale apparaît importante pour une stabilisation optimale de l’articulation et envisager une reprise des activités professionnelles et sportives.
Objectif
Étudier la relation entre la force musculaire des RI et RE et le niveau fonctionnel de l’épaule et la reprise sportive évalués de manière usuelle par des scores fonctionnels dans le cadre d’une stabilisation chirurgicale selon la technique de Latarjet pour une instabilité chronique de l’épaule.
Patients et méthodes
Vingt patients avec une instabilité antérieure chronique post-traumatique de l’épaule ont été inclus dans cette étude prospective de suivi de cohorte. Ils ont bénéficié d’une évaluation objective de la fonction de l’épaule opérée, par le score de Rowe et le score de Walch-Duplay, et de la force musculaire des RI et RE par évaluation musculaire isocinétique sur dynamomètre de type Con-Trex ® , en préopératoire et à trois, six et 21 mois postopératoires. L’évaluation isocinétique a été réalisée en position assise, bras à 45° d’abduction et 30° d’antépulsion dans le plan de la scapula, à 180°/s, 120°/s et 60°/s.
Résultats
Il n’existait pas de corrélation significative entre la fonction (score de Rowe et de Walch-Duplay) et la force musculaire des RI et RE, hormis en préopératoire.
Conclusion
Ce travail ne met pas en évidence de corrélation entre la force musculaire des RE et RI et les scores fonctionnels après stabilisation chirurgicale de l’épaule. Cependant, il est nécessaire de mesurer objectivement la force musculaire des rotateurs de l’épaule afin d’optimiser le renforcement musculaire nécessaire à la reprise des activités sportives. L’évaluation isocinétique peut donc représenter une aide à la décision de reprise sportive en complément des différents scores fonctionnels étudiés.
1
English version
1.1
Introduction
The glenohumeral joint is very mobile and is exposed to a high risk of instability and dislocation (anterior dislocation, in 90% of cases) . The bone and ligament components of static shoulder stability do not provide optimal congruence and may lose their ability to stabilize the joint after repeated episodes of dislocation . This is why dynamic stabilization components (i.e. the rotator cuff muscles) play a true role in maintenance of the glenohumeral joint and the permanent refocusing of the head of the humerus in the glenoid . The rotator cuff’s stabilizing effect has been clearly revealed by the dynamic balance between the internal (IR) and external (ER) rotators .
Surgical stabilization of the shoulder is currently considered to be the “gold standard” for the treatment of chronic, unidirectional, traumatic instability . Of the various procedures to have been described and used, the Bristow-Latarjet procedure (open surgery, with transfer of the horizontal branch of the coracoids to the anterior edge of the glenoid) gives good results and has a low recurrence rate (3% in the Sofcot series) . This procedure is particularly indicated in young subjects with post-traumatic anterior instability and who practice contact sports with a significant risk of shoulder trauma . However, the surgical approach – incision of the skin and the anterior shoulder muscles and tendons (notably the subscapularis tendon) – causes transient IR dysfunction and/or loss of strength . Since dynamic muscle-related factors play a role in the maintenance of glenohumeral stability , the postoperative recovery of strength is known to be essential for optimisation of dynamic stability and thus the resumption of sports or high-risk activities .
The outcome of surgical stabilization is usually evaluated by the application of functional tools (scores, indices or scales), such as the Rowe score, the Walch-Duplay score and (more recently) self-questionnaires like the Western Ontario Shoulder Instability Index (WOSI), the Shoulder Instability Questionnaire (SIQ) and the Melbourne Instability Shoulder Scale (MISS) . These tools are used to subjectively evaluate handicap, function, quality of life and/or pain and to objectively assess joint mobility . Although the Rowe and Walch-Duplay scores are most frequently used to assess shoulder instability, their metrological properties and validity have not been established.
Even though most researchers currently believe that muscle recovery is essential for the resumption of activity , the relationship between the level of muscle strength recovery and shoulder function has not been well characterized . The objective of the present study was to study the relationship between the IR and ER muscle strength, and the shoulder function and the resumption of sports activity (as typically evaluated with functional scores) following surgical stabilization with the Bristow-Latarjet procedure in cases of chronic shoulder instability.
1.2
Methods
1.2.1
Population
Twenty patients with chronic, post-traumatic, anterior shoulder instability were included prospectively. The inclusion criteria were as follows: chronic, symptomatic, post-traumatic, unilateral, anterior shoulder instability; age between 18 and 45; male gender; surgical stabilization by anterior coracoid transfer according to the Bristow-Latarjet procedure, following an initial episode of traumatic dislocation. The exclusion criteria were as follows: associated lesions (of the rotator cuff or bone) or any contra-indication to the performance of an isokinetic evaluation. All diagnoses of chronic shoulder instability and decisions to operate were made by the same orthopaedic surgeon (LB), in accordance with the latest guidelines .
The patients’ mean ± SD age at the time of surgery was 27 ± 8 (range: 19 to 45). The mean height was 179 ± 7 cm and the mean weight was 73 ± 9 kg. Eighteen patients were right-handed and two were left-handed. The dominant side was damaged in eight patients. The mean number of dislocations prior to surgery was 4 ± 3 (range: 1 to 10). The mean time interval between the first episode of traumatic dislocation and surgery was 4.7 ± 5 years (range: 0.5 to 20 years). Prior to the occurrence of instability, 17 of the 20 subjects had been participating in sports in which the arms are used or in which the shoulder is exposed to injury: five played football, four played combat sports (three judokas and one boxer), four played racket sports, three played other sports with arm use (basket ball, handball and swimming), one was a skateboarder and one was a runner. Two subjects did not perform any sporting activities.
After the provision of informed consent, each patient was rated in terms of shoulder function (on the side to be operated) with the Rowe score and the Walch-Duplay score . Rotator muscle strength was evaluated by using a Con-Trex MJ isokinetic dynamometer (CMV AG, Dübendorf, Switzerland) before surgery (PreOp) and then 3, 6 and 21 months afterwards postoperative (hereafter designated by “3PostOp”, “6PostOp” and “21PostOp”, respectively).
1.2.2
The surgical procedure
All the patients were operated on by the same shoulder specialist (LB), according to the Bristow-Latarjet procedure. Surgery took place under general anaesthesia and with the patient in the sitting position. After using a subcoracoid approach to the deltopectoral area over 3 cm, the cephalic vein was tilted outwards and the afferent veins were ligated. The coracoid apophysis was exposed by resection of the pectoralis minor tendon and the acromiocoracoid ligament. The surgeon performed osteotomy at the base of the coracoid with a reciprocating saw and then avivement on the inner aspect and made two holes in the coracoid apophysis with a 3.2-gauge drill. He then made an incision in line with the fibres of the subscapular tendon, followed by a vertical arthrotomy. The head of the humerus was held aside with a Trillat retractor. The surgeon then excised the Bankart lesion (i.e. the osteoperiosteal detachment) and performed avivement of the anterior aspect of the glenoid component. The coracoid process was attached with two 35-mm malleolar screws. The capsule was sutured to the stump of the coracoid. Closure was performed layer by layer over a Redon drain and then the skin was closed with a Vicryl Rapide ® absorbable continuous suture. The patient’s arm was immobilized by strapping it tightly against the thorax.
1.2.3
The rehabilitation program
All the patients underwent a rehabilitation program, with home visits from a private-practice, state-registered physiotherapist of their choice. The surgeon had suggested a rehabilitation program but each physiotherapist was free to adapt it as a function of his/her patient’s progress and status. From D0 to D21, the shoulder was rested, with the arm strapped against the front of the thorax. The patient started to make passive elbow and shoulder movements (as long as no pain was present) and finger and wrist movements. The patient was allowed to remove the strapping when showering. From D21 to D45, the patients received three physiotherapy sessions a week, with the objective of recovering joint amplitude. The rehabilitation had to be pain-free, exclusively passive and with anterior elevation only. Pendular movements were authorized two to three times a day. ER work before D45 was prohibited. At D45, active work and external rotation were authorized. At D90, the resumption of professional and all sports activities was authorized.
1.2.4
Functional assessments
For each patient, shoulder function was assessed in terms of the Rowe score and the Walch-Duplay score by the same examiner (PE). The Rowe score is the most frequently used tool in the literature on shoulder instability . However, this score has not been validated and its metrological properties have not been characterized . The Rowe score features three items on shoulder stability (50 points), mobility (20 points) and function (30 points) ( Table 1 ). The overall score entered by the physician is considered to be excellent when it ranges from 90 to 100 points, good from 75 to 89 points, fair from 51 to 74 points and poor below 50 points . The Walch-Duplay score is mainly used in the French-speaking world and has not been validated either . It includes four items on the return to sport (25 points), stability (25 points), pain (25 points) and mobility (25 points) ( Table 2 ). Similarly, the overall score is considered to be excellent when it ranges from 91 to 100 points, good from 76 to 90 points, fair from 51 to 75 points and poor below 50 points . The Walch-Duplay score’s “return to sport item” was also studied independently of the other items.
| Items | Score (points) | |
|---|---|---|
| Stability | No recurrence, subluxation, or apprehension | 50 |
| Apprehension when placing arm in certain positions | 30 | |
| Subluxation (not requiring reduction) | 10 | |
| True recurrence | 0 | |
| Mobility | 100% of normal external rotation, internal rotation and elevation | 20 |
| 75% of normal external rotation, internal rotation and elevation | 15 | |
| 50% of normal external rotation, and 75% of normal internal rotation and elevation | 5 | |
| 50% of normal internal rotation and elevation and no external rotation | 0 | |
| Function | No limitation in work and sports, little or no pain | 30 |
| Mild limitation, little pain | 25 | |
| Moderate limitation | 10 | |
| Marked limitation and pain | 0 | |
| Items | Score (points) | |
|---|---|---|
| Sport or daily activity if no sport practiced before the operation | Return to same sport, at the same level | 25 |
| Or no discomfort | 25 | |
| Back to same sport, but at a decreased level | 15 | |
| Slight discomfort in forceful movements | 15 | |
| Change in sport | 10 | |
| Slight discomfort during simple movements | 10 | |
| Stop sport | 0 | |
| Slight discomfort during simple movements | 0 | |
| Stability | No apprehension | 25 |
| Persistent apprehension | 15 | |
| Feeling of instability | 0 | |
| True recurrence | −25 | |
| Pain | No pain or pain during certain climatic conditions | 25 |
| Pain during forceful movements or when tired | 15 | |
| Pain during daily life | 0 | |
| Mobility | Pure frontal abduction against a wall: symmetrical | 25 |
| Internal rotation (IR), limitation < 3 vertebrae | ||
| External rotation in abduction (ER2), limitation to < 10% of the contralateral side | ||
| Pure frontal abduction against a wall < 150° | 15 | |
| IR: limitation < 3 vertebrae | ||
| ER2: limitation to < 30% of the contralateral side | ||
| Pure frontal abduction against a wall < 120° | 5 | |
| IR: limitation < 6 vertebrae | ||
| ER2: limitation to < 50% of the contralateral side | ||
| Pure frontal abduction against a wall < 90° | 0 | |
| IR: limitation > 6 vertebrae | ||
| ER2: limitation to < 50% of the contralateral side | ||
The Rowe and Walch-Duplay functional scores were chosen because they are the most frequently used in this field .
1.2.5
Muscle strength evaluation
The strength of the shoulder’s IR and ER muscles was evaluated on the isokinetic dynamometer by the same examiner (PE). This system is considered to be reliable and reproducible . We used the modified Davies position: the patient sat with his arm abducted by 45° and anteflexed by 30° (so that the dynamometer axis was in the plane of the scapula) and with the elbow flexed at 90° . The dynamometer axis was aligned with the joint’s rotational axis: it passed through the arm and thus enabled external and internal rotational movements of the shoulder to be measured. The positional parameters were identical in the preoperative and postoperative assessments. In the arm’s starting position (enabling determination of the movement angle), the elbow was flexed at 90° in an intermediate pronosupination position with neutral shoulder rotation. The maximum joint amplitudes were preset: 20° of internal rotation and 60° of external rotation, with an automatic, computer-controlled safety margin. These preset amplitudes were the same for all patients. The subject’s trunk was strapped to the dynamometer for greater stability. The subject was allowed to hold a handle on the contralateral side of the dynamometer, in order to perform the evaluation as efficiently as possible.
Each patient underwent a standardized evaluation procedure, preceded by a 6-minute, general warm-up on a handbike ergometer (the Ergotonic 4000 from Sopur GmbH, Heidelberg, Germany) and then a specific warm-up on the dynamometer with three series of six sub-maximal repetitions at 120°/s (in order to familiarize himself with the isokinetic contraction mode). The exercises were performed on the injured shoulder only. The peak torque (PT) values in Newton-metre (Nm) were recorded at 180°/s, 120°/s and 60°/s in a concentric mode, with respectively 10, five and three repetitions. There was a 1-minute rest interval between series. The patient was given verbal encouragement but could not use feedback from the device’s screen. The values were gravity-corrected and were only recorded on the injured side (with a view to comparison with the functional assessment).
1.2.6
Statistical analysis
For each variable, the means and standard deviations were determined and the distribution was tested for normality with a skewness test. The kurtosis coefficient was applied to flatten the distribution. An analysis of variance for repeated measures was used to test the effect of time (PreOp, 3PostOp, 6PostOp and 21PostOp) on the Rowe score, the Walch-Duplay score, the latter’s “return to sport” item, IR muscle strength and ER muscle strength. When the effect was significant, a Fischer’s Protected Least Significant Difference (PLSD) post-hoc test was performed. The relationships between IR/ER muscle strength at each angular velocity on one hand and shoulder function (according to the Rowe score, the Walch-Duplay score and the “return to sport” item) on the other was evaluated by calculating Pearson’s r correlation coefficient for the four time points tested (PreOp, 3PostOp, 6PostOp and 21PostOp). A Bravais-Pearson r table was used to determine the critical values beyond which the corresponding correlation coefficients were significant. Statistical analyses were performed using Excel ® (Microsoft, Redmond, CA) and Statview ® (Version 5.0, SAS Institute Inc., Cary, NC). The significance threshold was set to P < 0.05.
1.3
Results
The preoperative (PreOp) evaluations were performed at D-29 ± 31 days (range: 1 to 133) before surgery. The corresponding time points for the 3PostOp, 6PostOp and 21PostOp assessments were 85 ± 11 days, 203 ± 31 days and 21 ± 6 months, respectively. There were no complications after the surgery or during rehabilitation. At the 21PostOp assessment, one patient (5%) presented a recurrence of shoulder dislocation and another reported a feeling of instability but no dislocation or subluxation.
All the mean values for the Rowe and Walch-Duplay scores, the “return to sport” item and PTs are reported in Table 3 .
| PreOp | 3PostOp | 6PostOp | 21PostOp | |
|---|---|---|---|---|
| Function | ||||
| Rowe score out of 100 points | 47.1 ± 24.0 a | 64.3 ± 22.9 | 84.0 ± 16.2 | 88.3 ± 17.1 |
| Walch-Duplay score out of 100 points | 55.3 ± 25.1 b | 63.0 ± 19.2 | 86.0 ± 10.8 | 90.8 ± 13.7 |
| “Return to sport” item score out of 25 points | 6.5 ± 8.9 c | 8.0 ± 8.9 | 19.5 ± 6.5 | 21.9 ± 6.7 c |
| Isokinetic muscle strength | ||||
| IR | ||||
| 180°/s | 42.5 ± 9.5 b | 30.8 ± 9.6 | 41.0 ± 9.7 | 44.5 ± 9.4 c |
| 120°/s | 45.7 ± 9.9 a,b | 31.1 ± 9.4 | 43.2 ± 10.3 | 45.6 ± 9.8 |
| 60°/s | 45.9 ± 11.1 b | 32.1 ± 9.3 | 42.9 ± 9.6 | 46.6 ± 9.5 |
| ER | ||||
| 180°/s | 29.0 ± 7.0 b,c | 24.0 ± 4.5 | 30.0 ± 5.8 | 28.0 ± 5.0 |
| 120°/s | 33.0 ± 6.9 a,b,c | 26.4 ± 4.7 | 32.5 ± 6.7 | 30.4 ± 5.5 |
| 60°/s | 34.7 ± 7.3 b | 27.4 ± 4.8 | 33.6 ± 6.6 | 32.1 ± 5.7 |
a Significant correlation between the Rowe score and isokinetic muscle strength.
b Significant correlation between the Walch-Duplay score and isokinetic muscle strength.
c Significant correlation between the “return to sport” score and isokinetic muscle strength.
1.3.1
Functional evaluation
The Rowe score increased from one evaluation to another but the increase was only significant for the time intervals between the PreOp, 3PostOp and 6PostOp assessments ( P < 0.05) and not for the time interval between the 6PostOp and 21 PostOp assessments.
The Walch-Duplay score also increased from one evaluation to another but the only statistically significant increase occurred between the 3PostOp and 6PostOp assessments ( P < 0.05).
The score for the “return to sport” item also increased from one evaluation to another but, again, the only statistically significant increase occurred between the 3PostOp and 6PostOp assessments ( P < 0.05).
There was a significant correlation between the Walch-Duplay score and the Rowe score at all time points: PreOp, 3PostOp, 6PostOp and 21PostOp ( r > 0.44; P < 0.05).
According to the Rowe score, 95% of the patients had an excellent outcome and 5% had a fair outcome 21 months after surgery. In terms of the Walch-Duplay score, 90% had an excellent or good outcome and 10% had a fair outcome. In all, 75% of patients had returned to their sport at the same level as before the onset of instability. The two non-sporting patients were able to resume their professional activities without any problems.
1.3.2
Muscle strength assessments
At 3 months postoperative, the PT values for the IR and ER were significantly lower than those measured prior to surgery and then 6 and 21 months afterwards ( P < 0.05). There were no statistically significant differences between the PreOp, 6PostOp and 21PostOp values.
1.3.3
The relationship between muscle strength and functional indices
The only statistically significant pre-op correlations were observed for the Rowe score and the PT at 120°/s ( r > 0.44; P < 0.05) and for the Walch-Duplay score and the PT values at all angular velocities ( r > 0.44; P < 0.05) ( Table 3 ).
A statistically significant correlation ( r > 0.44; P < 0.05) was observed for the “return to sport” score on one hand and the PreOp PT for the ER at 180°/s and 120°/s and the 21PostOp PT for the IR at 180°/s on the other ( Table 3 ).
1.4
Discussion
The results of the present study on the surgical treatment of shoulder instability indicated the absence of correlation between IR and ER muscle strength (as evaluated by the measurement of the concentric isokinetic PT values) on one hand and shoulder function (as evaluated with the Rowe and Walch-Duplay scores) on the other, except in the presurgical assessment.
To the best of our knowledge, this is the first study of its kind. Nevertheless, Amako et al. reported a weak correlation between the isokinetic IR and ER muscle strength and the Rowe score at 4 years after surgical stabilization with a combined Bankart-Bristow procedure .
This disparity may be due to a number of methodological limitations: the low number of patients in the present study but (above all) the fact that permission to resume sports activities was given by the surgeon on the basis of joint-related and functional parameters and not objective parameters (such as the isokinetic muscle strength measured here).
In fact, the Rowe and Walch-Duplay functional scores are based on subjective parameters which do not take account of the recovery of muscle strength. These scores do not include any items relating to muscle status (either scored objectively or self-rated by the patient). Only joint mobility could be considered as an objective parameter, even though it is judged summarily in terms of a “percentage of recovery” by comparison with the healthy side. These scores primarily express the condition experienced by the patient, in view of the subjective nature of certain items – particularly the notions of stability and pain and even the “return to previous activities” item, which is very dependent on the patient, the type of activity and even the surgeon. These scores express a so-called functional result relative to the subject’s abilities but do not in any way constitute a determinant, objective tool for measuring stability in the physiological or physiopathological sense; joint mobility is the only objective parameter taken into account. Even though these scores are very frequently used to monitor the outcome of surgical stabilization of the shoulder, they have not been evaluated or validated .
However, even though muscle strength and the functional scores are not correlated (other than in the pre-op assessment), these parameters changed over time in a similar way during follow-up. Isokinetic muscle strength had recovered at 6PostOp and was maintained at 21PostOp. Likewise, there was a concomitant resumption of sporting activities at 6PostOp and this was maintained at 21PostOp.
Hence, these scores may represent the subjective evaluation of a therapeutic outcome. They express the patient’s perceived status and so may correspond to “patient satisfaction” rather than an objective post-op outcome. However, objective clinical evaluations would be of value in managing the patient’s rehabilitation and physical medicine program in general and in determining the optimal resumption of physical and sports activities in particular . In view of our present results, muscle strength and functional status appear to be complementary indicators of the change over time in the condition of an operated shoulder. The post-operative evaluation of muscle strength helps optimize analytical rehabilitation by conditioning the physiotherapy program . According to Amako et al., muscle strength must reach at least 90% of the healthy contralateral value if resumption of high-level sport activities is to be envisaged . This objective appears to be even more necessary for the resumption of throwing sports in which the notion of performance is important . Thus, the objective evaluation of muscle strength has several objectives during post-operative follow-up: management of the rehabilitation program, objective evaluation of the therapeutic outcome and determination of the patient’s ability to resume physical and sports activities.
These considerations raise the question of the need to score the recovery of muscle strength, just as mobility and pain are monitored. Although muscle recovery is considered to be essential for the resumption of certain activities, this parameter does not feature in the frequently used but non-validated functional scores studied here . Other functional scores (such as the Constant score) take account of muscle strength (a measurement of static resistance for 5 seconds by holding a weight in 90° of abduction and with the elbow fully extended, repeated five times) . This test appears to be unreliable for the evaluation of unstable shoulders. The reproducibility is good but the construct validity and sensitivity to change are unknown . The WOSI 21-item self-questionnaire (evaluating certain aspects of quality of life in patients with shoulder instability) has a validated construct and good reproducibility and sensitivity to change but is rarely used . The equally little-used SIQ and MISS self-questionnaires appear to be relevant but have less good metrological qualities than the WOSI . Moreover, none of today’s scores and indices can predict the return to sports activities . Thus, the development of a score which is specific for shoulder instability (including subjective patient satisfaction and quality of life parameters and objective stability and muscle strength parameters) could improve both rehabilitation follow-up, the evaluation of outcomes and the resumption of sports activity.
1.5
Conclusions
The present study did not identify a relationship between the ER or IR muscle strength (as assessed using isokinetic dynamometry) and the functional status (as evaluated by the Rowe and Walch-Duplay scores) after surgical stabilization of the shoulder. However, the evaluation of isokinetic muscle strength appears to be relevant for optimizing muscle recovery and perhaps determining the return to sport. It would be useful to build a score, which include isokinetic muscle strength evalutation after surgical stabilization of the shoulder.
2
Version française
2.1
Introduction
L’articulation glénohumérale est une articulation très mobile, exposée à des risques fréquents de luxation, notamment antérieure (90 %), et d’instabilités . Les éléments osseux et ligamentaires de stabilité statique n’offrent pas une congruence optimale et peuvent avoir une capacité diminuée suite aux épisodes répétés de luxation . C’est pourquoi, les éléments de stabilisation dynamique représentés par l’activité des muscles de la coiffe ont un véritable rôle dans le maintien de l’articulation glénohumérale et le recentrage permanent de la tête humérale dans la glène . Cette activité musculaire stabilisatrice de la coiffe des rotateurs est identifiée cliniquement par l’équilibre musculaire réalisé entre les muscles rotateurs internes (RI) et rotateurs externes (RE) .
La stabilisation chirurgicale de l’épaule est considérée actuellement comme le « gold standard » pour le traitement de l’instabilité chronique traumatique unidirectionnelle . Parmi les différentes techniques décrites et utilisées, la technique de Latarjet (Bristow-Latarjet pour les Anglo-Saxons ), chirurgie à ciel ouvert, avec le transfert de la branche horizontale de la coracoïde sur le bord antérieur de la glène scapulaire, donne de bons résultats avec un faible taux de récidive (3 % dans la série de la Sofcot) . Cette technique est particulièrement indiquée pour les sujets jeunes souffrant d’une instabilité antérieure post-traumatique et pratiquant des sports de contact avec un important risque traumatique pour l’épaule . Cependant, la voie d’abord chirurgicale incisant les éléments cutanés et musculotendineux antérieurs de l’épaule, et notamment le tendon du muscle sub-scapulaire, est à l’origine d’un dysfonctionnement et/ou d’un déficit de force transitoire des muscles RI de l’épaule . Les éléments musculaires de stabilité dynamique ayant un véritable rôle dans le maintien de la stabilité glénohumérale , la récupération de leur force en postopératoire est reconnue comme indispensable pour une optimisation de la stabilité dynamique post-chirurgicale afin d’envisager une reprise des activités sportives et/ou à risque pour l’épaule .
L’analyse des résultats de la chirurgie de stabilisation est le plus souvent évaluée par des outils fonctionnels (scores, index ou échelles), tels que le score de Rowe, de Walch-Duplay (ou Duplay), ou plus récemment les autoquestionnaires de Western Ontario Shoulder Instability Index (WOSI), Shoulder Instability Questionnaire (SIQ) et Melbourne Instability Shoulder Scale (MISS) . Ils évaluent de manière subjective l’incapacité, la fonction, la qualité de vie et/ou la douleur, et de manière objective la mobilité articulaire . Les scores de Rowe et de Walch-Duplay sont les plus utilisés dans l’instabilité de l’épaule, mais leur qualité métrologique et leur validité ne sont pas connues.
Si, selon les données actuelles, la plupart des auteurs jugent comme indispensable la récupération musculaire pour la reprise de certaines activités , inversement la relation entre le niveau de récupération de la force musculaire et le niveau fonctionnel de l’épaule n’est pas clairement connue . L’objectif de notre étude était d’étudier la relation entre la force musculaire des RI et RE et le niveau fonctionnel de l’épaule et la reprise sportive évalués de manière usuelle par des scores fonctionnels, dans le cadre d’une stabilisation chirurgicale selon la technique de Latarjet pour une instabilité chronique de l’épaule.
2.2
Méthodes
2.2.1
Population
Vingt patients avec une instabilité antérieure chronique post-traumatique de l’épaule ont été inclus selon une méthode prospective de suivi. Les critères d’inclusion étaient : patients souffrant d’une instabilité antérieure chronique, symptomatique, post-traumatique et unilatérale de l’épaule, âgés de 18 à 45 ans, de sexe masculin, devant bénéficier d’une stabilisation chirurgicale par butée antérieure coracoïdienne selon la technique de Latarjet, ayant eu un premier épisode de luxation traumatique. Les critères d’exclusion étaient : une lésion associée (lésions de la coiffe des rotateurs, lésions osseuses…), une contre-indication à la réalisation d’une évaluation isocinétique. Le diagnostic d’instabilité chronique de l’épaule et l’indication opératoire ont été posés par le même chirurgien orthopédiste (LB) selon les recommandations actuelles .
L’âge moyen des patients au moment de l’intervention était de 27 ± 8 ans (de 19 à 45 ans), la taille moyenne de 179 ± 7 cm et le poids moyen de 73 ± 9 kg. Dix-huit patients étaient droitiers et deux gauchers. Le côté dominant était lésé pour huit patients. Le nombre moyen de luxations avant la chirurgie était de 4 ± 3 (de 1 à 10 épisodes). Le délai moyen entre le premier épisode de luxation traumatique et la chirurgie était de 4,7 ± 5 ans (de 0,5 à 20 ans). Dix-sept patients parmi les 20 pratiquaient un sport sollicitant ou à risque pour les membres supérieurs avant la survenue de la pathologie d’instabilité : cinq pratiquaient du football, quatre des sports de combat (trois judo et un boxe), quatre des sports de raquette, trois des sports sollicitant les membres supérieurs (un basketball, un handball et un natation), un le skate board et un la course à pied, et deux ne pratiquaient pas de sport.
Après le recueil du consentement éclairé, chaque patient inclus a bénéficié d’une évaluation de la fonction de l’épaule opérée par le score de Rowe et le score de Walch-Duplay . La force musculaire des rotateurs a été évaluée à l’aide d’un dynamomètre isocinétique Con-Trex ® (Con-Trex MJ ; CMV AG, Dübendorf, Suisse), en préopératoire (PréOp), à trois mois postopératoires (3PostOp), à six mois postopératoires (6PostOp) et à 21 mois postopératoires (21PostOp).
2.2.2
Procédure chirurgicale
Tous les patients ont été opérés par le même chirurgien spécialiste de l’épaule (LB) selon la technique de Latarjet. L’intervention chirurgicale a eu lieu sous anesthésie générale, le patient en position assise. Par un abord de l’espace deltopectoral, sous-coracoïdien sur 3 cm, la veine céphalique est réclinée en dehors et les veines afférentes ligaturées. L’apophyse coracoïde est exposée par la section du tendon du petit pectoral et du ligament acromiocoracoïdien. Le chirurgien procède à l’ostéotomie de la coracoïde à sa base à la scie oscillante, à l’avivement de sa face inférieure, et à la réalisation de deux trous à la mèche 3,2 dans l’apophyse coracoïde. Puis il réalise une incision dans le sens des fibres du tendon du sub-scapulaire, suivi d’une arthrotomie verticale. La tête humérale est écartée par l’écarteur de Trillat. Le chirurgien procède à l’excision du décollement ostéopériosté de Bankart, à un avivement de la face antérieure de la glène. La fixation de la butée est réalisée par deux vis malléolaires d’environ 35 mm. Il réalise une suture de la capsule au moignon de ligament coracoïdien. La fermeture est faite plan par plan sur un drain de redon aspiratif, puis la peau est fermée par un surjet au Vicryl à résorption rapide. Le patient est immobilisé par un bandage coude au corps.
2.2.3
Procédure de rééducation
Tous les patients ont bénéficié d’une prise en charge en rééducation, avec un masseur-kinésithérapeute diplômé d’état en exercice libéral de leur choix. Un programme de rééducation défini par le chirurgien sert de guide, mais il peut être adapté en fonction de l’évolution du patient. De j0 à j21, l’épaule est mise au repos, immobilisée par un bandage coude au corps. Le patient débute des mobilisations passives du coude et de l’épaule, en respectant la règle de la non-douleur, associées à des mobilisations des doigts et du poignet. L’ablation de la contention est autorisée pour la toilette. De j21 à j45, les patients bénéficient de trois séances de kinésithérapie par semaine avec un objectif de récupération des amplitudes articulaires. La rééducation doit être indolore, en passif exclusivement, en élévation antérieure. Des mouvements pendulaires sont autorisés deux à trois fois par jour. Le travail des RE est proscrit avant j45. À j45, le travail actif et en rotation externe est autorisé. À j90, la reprise du travail et de toute activité sportive est autorisée.
2.2.4
Évaluation fonctionnelle
L’évaluation fonctionnelle de l’épaule a été réalisée pour chaque patient par le score de Rowe et le score de Walch-Duplay, ou Duplay , par un même examinateur (PE). Le score de Rowe est le score le plus souvent utilisé dans la littérature touchant à l’instabilité d’épaule . Cependant, il n’est pas validé et ses critères métrologiques ne sont pas connus . Il comprend trois items évaluant : la stabilité (50 points), la mobilité (20 points) et la fonction (30 points) ( Tableau 1 ). Le total permet d’apprécier le résultat objectif, en considérant un score comme excellent de 90 à 100 points, bon de 75 à 89 points, moyen de 51 à 74 points et mauvais à moins de 50 points . Le score de Walch-Duplay utilisé essentiellement dans les études francophones, n’est pas non plus validé . Il comprend quatre items : la reprise du sport (25 points), la stabilité (25 points), la douleur (25 points) et la mobilité (25 points) ( Tableau 2 ). Le score total permet d’apprécier le résultat objectif, en considérant un score comme excellent de 91 à 100 points, bon de 76 à 90 points, moyen de 51 à 75 points et mauvais à moins de 50 points . L’item du score de Walch-Duplay concernant la reprise du sport a été étudié de manière indépendante des autres items.
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