J.Orthopaedics 2011;9(1)e3

Keywords:

shoulder dislocation, axillary artery, injury

Introduction:

The estimated incidence of shoulder dislocation is approximately 1.7% [1,2]. Chalidis et al. showed in a recent study that falling was the most frequent mechanism of injury and that the overall recurrence rate was 50% in all ages, 89% in patients younger than 20 years [3]. Vascular injuries are exceptional with approximately one reported case every year.

Case Report:
An 81 year old woman was admitted to the emergency department for a Left shoulder trauma 2 hours after a fall while she was doing her daily walking sport activity. Her initial clinical exam raised a suspicion of an anterior dislocation with no previous history of such incident. She had preserved motor function but signaled that her left hand was numb. Her radial pulse was present and strong. The radiographs showed an anterior dislocation of the scapula-humeral joint with a mildly displaced fracture of the trochiter and a calcified axillary artery. After administrating intra-venous analgesics a reduction of the dislocated shoulder was attempted using the Hippocrates’ maneuver; it was a long and difficult reduction and before sending the patient for x-rays the shoulder was re-dislocated with a complete abolition of the radial pulse at that time. The attending orthopedic surgeon was then contacted and a second attempt, under general anesthesia, was successful; the radial pulse was fully restored and the limb color was back to normal. The radiographs confirmed the reduction. The patient was discharged at home.

Twenty-four hours later the patient was re-admitted for an acute pain in her left upper limb with all the signs of a sub-acute ischemia. An important hematoma in the axillary and supra-clavicular region was noted extending to the antero-medial aspect of the arm. There were no signs of compartmental syndrome. The angiography showed an abrupt occlusion of the distal axillary artery with distal collateral supply to the brachial artery at its mid-level [Fig. 1]. Two hours after the admission the vascular surgical team was performing an exploration through an infra-clavicular approach; a thrombosis was found in the retro-pectoral part of the axillary artery associated with a partial adventitial transection. Reconstruction was performed with a reversed saphenous vein and an end-to-end anastomosis. The compartments of the upper extremity were normal after revascularization. The patient had a normal neurovascular status with Doppler evidence of a patent graft six months after her surgery. The trochiter fracture was healed and no recurrent instability was noted. A written informed consent was obtained from the patient prior to the publication of this Case report.

Discussion
Injuries of the axillary artery after a dislocation of the shoulder are very uncommon in the recent literature but such complication was not infrequent when reviewing the literature of the first half of the last century. In 1911, Guibe [4] collected 78 observations of vascular complications related to shoulder dislocations. Calvet et al. [5] reported that 73 over 90 documented cases of artery injuries were observed after the reduction maneuver and discussed the medico-legal aspect of this complication. The high rate of complications was probably due to the forceful methods, yet widely used at that time, on old dislocations (64 over 91 cases according to Calvet et al.) and without anesthesia with ligation as the sole treatment at that time. After the common use of powerful analgesics and/or general anesthesia this rate dropped dramatically; Rowe [6] couldn’t find any arterial injury over a series of 500 dislocations.

The hemorrhage due to an injury to the axillary artery might be fatal. Watson-Jones [7] described the case of an elderly man with a recurrent dislocation of the shoulder reduced by the patient himself until the day when his atherosclerotic artery ruptured causing his death.

Dislocation type seems to be a predisposing factor for some authors where the anterior dislocation comes second to the inferior dislocation in terms of complication frequency [6,7]. Intrathoracic and sub-clavicular dislocations also seem to be prone to arterial injuries according to Fontaine et al. [8].

Blunt trauma usually causes injury to the third segment of the axillary artery positioned under the lower edge of pectoralis minor, which is relatively anchored by the branches of the circumflex humeral and subscapular arteries [9].

In up to a third of patients there is a history of previous dislocation [10], suggesting that the initial injury may cause the artery to be fixed by inflammatory tissue in the torn shoulder joint capsule; this renders it more susceptible to injury with subsequent dislocations [11].

Over 90% of reported cases of vascular injury following shoulder dislocation occur in patients over the age of 50 [12, 13]. Allie et al described three possible mechanisms for the axillary artery injury; a) sudden kinking of the artery over the edge of pectoralis minor, b) entrapment of the artery by fibrotic adhesions between the joint capsule and the artery, c) direct or transmitted pressure on a non-elastic atherosclerotic artery predisposing it to damage by a dislocated humeral head [13]. Our patient had a calcified axillary artery on x-rays; such radiological sign, when present, indicates an important loss of elasticity due to arteriosclerosis and need to be considered as a red flag for arterial injuries.

We cannot emphasize more on the importance of the neurovascular clinical assessment following a shoulder dislocation; Allie et al. estimated the incidence of an axillary mass and the absence of distal pulse on admission to be 71% and 93% respectively [13], but there it was rarely mentioned whether these signs were recorded before or after reduction, for a first episode dislocation.

The literature is abundant in the number of described techniques to reduce an anterior dislocation of the shoulder; many of them are “soft” and non traumatic. Details of reduction techniques were generally underreported for shoulder dislocations associated to vascular injuries. We believe, as many others that Hippocrates’ maneuver is a brutal method for reducing a dislocated shoulder and this could be more relevant in elderly people with inelastic vessels. We don’t know, for our patient, if the axillary injury was due to the dislocation mechanism, to the repetitive and difficult attempts with the Hippocrates’ maneuver or to their association. We believe that this forceful technique could be a possible mechanism or a risk factor to axillary injuries. Gibson postulated that the hyperabducted humeral head exposes the axillary artery which then bends it against the fulcrum of the edge of pectoralis minor leading to vascular injury [14].We recommend abandoning this technique or any other technique using abduction for reduction.

Conclusion

Vascular complications as a result of shoulder dislocation or after reduction are very rare. The case we present is a reminder to clinically assess the neurovascular status of the upper limb before and after the reduction maneuver and to seek further investigation in case of doubt. Reduction maneuvers need to be gentle, particularly in elderly people whose arteries are often atherosclerotic. The use of adequate analgesia is important in helping to insure that reduction is possible without repeated forceful attempts.

References: