Chir Organi Mov (2008) 91:79–83 DOI 10.1007/s12306-007-0013-4

O R I G I NA L A RT I C L E

Posterior shoulder pain and anterior instability: a preliminary clinical study Alessandro Castagna • Marco Conti • Mario Borroni • Giuseppe Massazza • Enzo Vinci • Giorgio Franceschi • Raffaele Garofalo

Received: 3 September 2006 / Accepted: 25 September 2006ccepted: 23 October 2006 / Published online: … … … © Springer-Verlag 2008

Abstract Different clinical tests have been suggested in the literature as significant indicators of anterior shoulder instability. Sometimes patients with recurrent anterior shoulder instability may show some muscular guarding thus making the evaluation of specific clinical tests very difficult. These patients may also report a medical history with posterior shoulder pain that can be also elicited during some clinical manoeuvres. From September 2005 to September 2006 we prospectively studied patients who underwent an arthroscopic anterior capsuloplasty. Shoulder clinical examination was performed including anterior shoulder instability tests (drawer, apprehension and relocation tests). Furthermore the exam was focused on the presence of scapular dyskinesia and posterior shoulder pain. The patients were also evaluated with ASES, Rowe, SST (Simple Shoulder Test), Constant and UCLA (University of California at Los Angeles) scoring system preoperatively and at the latest follow-up time. In the period of this study we observed 16 patients treated for anterior gleno-humeral arthroscopic stabilisation, who preoperatively complained also of a posterior scapular pain. The pain was referred at the level of lower trapezium and upper rhomboids tendon insertion on the medial bor-

der of the scapula. It was also reproducible upon local palpation by the examiner. Four of these patients also referred pain in the region of the insertion of the infraspinatus and teres minor. After arthroscopic stabilisation the shoulder was immobilised in a sling with the arm in the neutral rotation for a period of 4 weeks. A single physician supervised shoulder rehabilitation. After a mean time of 6.8 months of follow-up, all the shoulder scores were significantly improved and, moreover, at the same time the patients referred the disappearance of the posterior pain. Posterior scapular shoulder pain seems to be another complaint and sign that can be found in patients affected by anterior shoulder instability. It can also be related to eccentric work of posterior stabilising muscles of scapula during the altered biomechanics observed in case of anterior shoulder instability. This pain responds positively to surgical intervention showing that re-centring the humeral head probably also re-establishes the periscapular muscle-firing pattern with a mechanism mediated by the proprioceptive system. Keywords Anterior instability · Shoulder · Posterior pain · Instability · Apprehension

Introduction

A. Castagna · M. Conti · M. Borroni · G. Massazza · E. Vinci G. Franceschi Unità di Chirurgia della Spalla “IRCCS Istituto Clinico Humanitas” Rozzano, Milan, Italy R. Garofalo () Ortopedia e Traumatologia Ospedale “F. Miulli” 70021 Acquaviva delle Fonti (BA) e-mail: [email protected]

The gleno-humeral joint is the most mobile joint of the human body. This feature makes this joint susceptible to dislocation. Anterior traumatic shoulder dislocation is the most common type of shoulder instability observed by clinicians [1, 2]. Different clinical tests have been indicated in the literature as positive and significant for anterior shoulder instability. The apprehension and relocation tests are the most commonly used and validated to clinically assess

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stability disorders of the shoulder [1, 3–5]. In particular, shoulder surgeons perform these tests before surgical management and at follow-up. The resolution of these tests after surgery is considered as a sign of good outcome. Sometimes the patients complaining of recurrent anterior shoulder instability may present some muscular guarding that makes the assessment of these tests difficult and questionable. Nevertheless, this group of patients often also report spontaneous and persistent posterior scapular pain in their medical history, which can also be elicited during some dynamic manoeuvres at clinical examination. This kind of pain must be differentiated from the posterior pain, described as a sign of shoulder instability, reported by some patients during the apprehension and relocation test [1, 6–8]. To our knowledge there are no reports in the literature on the presence and frequency of posterior scapular pain not associated to provocative manoeuvres in patients affected by anterior shoulder instability. The scapula plays a key role in shoulder biomechanics [9]. In particular, the entire scapula is intimately involved in shoulder function; in fact a scapular dyskinesia has been reported in between 67% and 100% of patients with gleno-humeral instability of all causes [10–12]. Despite frequently reported scapular dyskinesia, however, no author has underlined and discussed the presence of posterior scapular pain in this group of patients. The aim of this study, therefore, is to determine the presence and pattern of posterior shoulder pain in patients affected by anterior shoulder instability and discuss the relationship between them. The hypothesis was that the pain is associated with scapular dysfunction and muscular imbalance related to anterior shoulder instability and once shoulder instability is surgically addressed, the pain should disappear.

Methods We prospectively selected patients operated on with an arthroscopic capsule-labral repair because of anterior shoulder instability from September 2005 to September 2006. The criteria for inclusion in this study were the presence of a clear history of repeated anterior subluxation or dislocation following an initial episode of anterior instability caused by a traumatic event, an occult anterior shoulder instability with symptom duration not shorter than 6 months, no previous shoulder surgery and motivation to undergo a surgical repair. A single experienced clinician (MC) evaluated the patients preoperatively. A complete shoulder examination was performed and in particular the tests of anterior shoulder instability (apprehension and relocation tests) were performed. Then the examiner focused his attention on the presence of scapular dyskinesia and posterior scapular pain. Patients were assessed

Chir Organi Mov (2008)

also by mean of ASES, Rowe, SST (Simple Shoulder Test) and UCLA (Constant and University of California at Los Angeles) scoring system preoperatively and at the latest postoperative evaluation. The statistical analysis was done using Student’s t-test to compare the difference between the pre- and postoperative scores, for paired data. The significance level was set at p