Understanding cycling shoulder injuries
By Joe F de Beer
Cycling injuries account for 500,000 visits per year to emergency rooms in the US. Over half the accidents involve motor vehicles. Of participants in cycle events, 0,4% up to 10% sustain serious injuries, which are significantly more frequent in women than in men. The most common mechanism of injury involves a forward fall over the handlebars on the shoulder or on the outstretched arm resulting in direct or indirect lesions of the upper extremity. The most common bony injury is a clavicle fracture, which represents around 45% of all recorded fractures due to bicycle accidents. Other orthopedic lesions of the shoulder include Acromioclavicular (AC) joint dislocations, proximal humeral fractures, shoulder dislocations, rotator cuff tears and scapular fractures. Many of the above mentioned shoulder injuries can be treated conservatively but some may require surgical repair. We will discuss the different pathologies and their management.
1. Fractures of the Clavicle (Collar bone).
The clavicle, or collarbone, is a bone that is a part of the shoulder girdle. It serves as a solid support to the arm. It is essential for full range movement of the arm, it forms the upper part of the canal (“thoracic outlet”) between the neck and the arm and it transmits the force of an impact on the arm to the body. The latter is one of the reasons why it is such a commonly fractured bone. The clavicle is connected to the shoulder blade with the acromio-clavicular and the coraco-acromial ligaments.
Furthermore, the clavicle is also prone to fracture because of its very superficial localisation. The annual incidence of clavicular fractures is suspected to be around 50-100,000 in the USA. Bicycle accidents most frequently cause clavicular fractures and the clavicle is the most common bony injury of all recorded fractures due to bicycle accidents. A direct fall on the shoulder is the most frequent mechanism of injury followed by a fall on the outstretched arm whereby the force is transmitted to the collar bone.
The middle third of the clavicle is the weakest point where it is most commonly fractured (75% – 85%) (fig 1), while the lateral third of the clavicle is fractured in about 15% of all clavicle fracture cases (fig 2). These lateral clavicle fractures are often associated with a rupture of the ligaments between the clavicle and the coracoid of the shoulder blade and tend to lead more to non union if treated conservatively.
Figure 1: Mid shaft clavicular fracture.
Figure 2: Distal clavicular fracture with torn coraco-acromial ligaments.
Clavicle fractures are most commonly treated non-operatively. Herefore the arm needs to be kept in a sling for 4 to 6 weeks. Of “historic” importance was the use of “figure of 8” bandages to try and reduce and immobilise the clavicle but they are not used any longer due to the extreme discomfort caused by those bandages and their relative ineffectiveness. It takes 6 to 8 weeks before solid healing is obtained. Once the callus is strong enough, one will be advised to start with a home based exercise programme. Initially passive mobilisation will be allowed. In the following weeks an increase of the intensity of the exercises and active exercises can be done. Until healing has taken place heavy activities and sport, where falls and other blows could be expected, should be avoided. The clavicle could still refracture at the previous point of fracture and one should wait for about 3 months before such activities are embarked upon, unless the risk is acceptable to the participant in the sport.
On the other hand, surgical treatment is an option. It allows for an earlier start of activities and pain is also diminished by fixing the fracture. Absolute indications for surgery are: 1) skin penetration, 2) associated nerve or vascular trauma and a painful non-union of the fracture. Relative indications are 1) a significant shortening of the clavicle (1,5 cm and more), 2) severe angulation and lateral clavicular fractures because these have a non union rate of 20% up to 50% if treated conservatively. It is important to realise that the displacement of the fracture fragments will not improve after healing has taken place, therefore it is important to make a decision about surgery within the first few days after the injury.
c) Surgical technique
Different methods of fixation of these fractures exist but plate and screw fixation is most commonly used (figure 3). This method has stood the test of time and allows for early mobilisation of the shoulder and has a high success rate.
Internal fixation with plate and screws for clavicular fracture.
The plate can remain on the clavicle permanently but removal could be considered for two reasons; firstly, in some (especially thin individuals) the plate may be prominent and cause irritiation of the skin, secondly, in sports where falls on to the shoulder can be expected (e.g. mountain biking and motorcycle racing) a repeat fall could fracture the clavicle again. The problem is that the repeat fracture usually does not occur through the previous site but medial (on the side of the breast bone) to the plate, which is more close to the large blood vessels and nerves of the retro sternal region.
In such cases the plates are most often removed after 6 to 9 months. Other methods of fixation of the clavicle are “intra-medullary” methods such as Haggie pins or Sonoma rods (figure 4). These small rods are placed inside the shaft of the clavicle and have the advantages that the skin incision and resulting scar are much smaller than for the plates. The disadvantage however is a less stablefixation resulting in a higher non union rate.
In distal clavicular fractures one often has to deal with a small lateral bone fragment which does not allow for adequate screw placement. These types of fractures are often treated by reduction and wire fixation via transosseous tunnels.
The outcome of those methods is often less optimal. The senior author favours a method of fixing the proximal fragment ( the clavicle) to the coracoid with tape,which reduces the fracture to al large degree and then the distal fragment to the proximal with additional tape. Another method of treating this distal clavicular fractures is the use of a hooked plate. We do not encourage the use of this plate for several reasons; 1) A second surgery is alway necessary to remove the plate after 3 months, 2) no abduction of more than 90° is allowed with the plate in place, 3) Harm to the subacromial space often occurs and 4) the complications are often difficult to treat.
The most common complications of osteosynthesis of the clavicle are non-union (the fracture does not heal) and infection. These complications do not occur frequently but have to be regarded due to the fact that the clavicle is a bone which is very superficial under the skin. The hook plate has to deal with the same complications but also has the risk of destroying the acromion (figure 5).
Figure 5: A hook plate used for a distal clavicular fracture. The postoperative phase was complicated by subacromial erosion by the plate.
The union rate of clavicular fractures is very high both in the conservative and surgical group. Predisposing factors for non-union are skin perforation by the bone, the association of other lesions, mobilisation being too early and smoking. Smoking increases the risk for non-union because of its known negative influence on fracture healing. If a non-union is present, whether there was previous conservative or operative treatment, the best management is surgery: stabilisation with plate and screws and inserting bone stimulating substances (BMP), either commercially available or by harvesting bone from the hip bone (iliac crest). The rehabilitation is the same as for initial surgery.
2. AC joint dislocations
The acromio-clavicular joint is the connection between the clavicle (collar bone) and the acromion (shoulder bone). This injury usually results from a fall onto the tip of the shoulder or on to the back of the shoulder. The acromion is driven downwards and the tip of the clavicle remains behind; this can result in tears of the acromio-clavicular and the coraco-acromial ligaments, which normally hold them together. Although the injury usually appears like the collar bone is pointing into the air, it is actually the other way around, with the shoulder blade hanging down (figure 6). The injury is graded into different types depending upon the number of ligaments torn and direction of the dislocation. The diagnosis of an AC joint dislocation is mostly made clinically but must be confirmed on X-ray to determine the type in order to decide on the treatment. The use of the Zanca view (figure 6) and the lateral axilary view is advised. The Zanca view is a 15° cephalad orientated view which allows for lower penetration images and no superimposition on the posterior acromion and lateral scapular spine on the clavicle. The lateral axillary view allows for the detection of small fractures and posterior displacement of the clavicle. The routine use of stress views is no longer advised.
Figure 6: Ac joint dislocation with disruption of the coraco-clavicular and the acromio-clavicular ligaments.
Type I and II: Patients with these injuries usually experience pain over the AC joint and there is swelling. They are usually managed conservatively and surgery is not necessary. Conservative treatment includes ice, rest and physiotherapy. A shoulder sling is not necessary to aid healing of the ligaments. The recovery is usually full with return to full and painless activity within a few weeks. Return to sport and other activities is safe as soon as the pain has settled.
Type III: Does not require surgery in the majority of cases and can be managed conservatively. It is very seldom necessary to do an operation in the early period after the injury.
The reasons are the following
- In a majority (more than 80%) of these injuries, there will be complete recovery of pain and return to normal function.
- In the small number, which do not recover as mentioned above, a late repair is as successful as an early repair. This implies that, should one do an early repair in everybody there is an 80% chance that this could be unnecessary surgery.
- Any surgery does carry a complication rate (even if it is low) and one should therefore only do such operations on those that have proven that they will not recover from their pain and return to function.
- Scapular Malpositioning and Rotatory Instability of the scapula: Those AC joint dislocations that do remain symptomatic are usually due to the fact that the shoulder blade is displaced downwards, pulling on the nerves above the shoulder as well as the muscles stabilising the scapula – causing symptoms into the shoulder and down the arm resulting in lameness, tingling of fingers and pain at the back in the area of the shoulder blade.
Type IV and V: Early repair of these dislocations is usually indicated. These patients usually have a lot of pain due to the fact that the tip of the collar bone protrudes into the overlying trapezius muscle and non- operative management does not have a favourable outcome
c) Surgical technique
Different surgical techniques exist to treat AC joint dislocations. We will describe our preferred method which consist of a strong repair to reduce the dislocation and which allows for biological healing. We do not recommend use of metal hardware such as plates/ screws due to the association of these with complications. Our procedure can be regarded as a “modified Weaver-Dunn” procedure with added stabilisation of the AC joint with a tendon graft.
The surgical procedure we do is to reconstruct the dislocated AC joint with a specific method: The coraco-acromial (CA) ligament is detached from the acromion and transferred to the tip of the collar bone –to take over the function of the torn ligaments. Further reinforcement is done by placing a graft between the tip of the clavicle and the shoulder bone. The purpose of this procedure is to not only realign the AC joint but also realign the shoulder blade to take the tension off the nerves of the brachial plexus. This realignment of the shoulder blade relieves the traction on the nerves and cures the symptoms in the arm. Post-operative, a sling will be worn for about 3 weeks and during this post-operative time the patient is permitted to do movements of the arm without stressing it heavily. Gradual motion to normal activities will be permitted.
3. Humeral fractures
Proximal humeral fractures are much less frequent than the above-mentioned injuries but do often occur after a bicycle accident. These injuries mostly occur during a fall on the outstretched hand however a direct blow to the shoulder may also cause these fractures.
These fractures can be simply classified into four groups. Various combinations of these groups may occur.
- Fractures of the greater tuberosity.
- Fractures of the lesser tuberosity.
- Fractures of the surgical neck.
- A combination of 2 or 3
(1) Greater tuberosity fractures
These account for a small number of proximal humeral fractures, and are associated with shoulder dislocations. Furthermore a direct injury to the shoulder can break the tuberosity into several fragments.
(2) Lesser tuberosity fractures
These usually result from posterior shoulder dislocations or from violent muscle contraction and are very seldom the result of a bicycle accident.
(3) Surgical neck fractures
These are the result of a fall on the outstretched arm as can occur in bicycle accidents.
(4) A combination of 2 or 3 from these fractures will result in 3 or 4 part fractures.
Non-displaced fractures with little angulation or rotation can be treated conservatively with an immobilization in a sling for 3 to 6 weeks. Most fractures however are treated with surgery seen the young age of this group and the high impact of the accident. Depending on the fracture type, screws, plate and screws, metal wires or suture-anchors can be used. Greater tuberosity fractures need to be treated as a large rotator cuff tear of the supraspinatus muscle. This can be done by open or arthroscopic surgery and with the use of bony tunnels or suture-anchors. The use of arthroscopic surgery allows for the treatment of associated rotator cuff tears. I f surgery is required for surgical neck fractures or 3 or 4 part fractures of the humeral head, open surgical fixation can be performed using plate and screws. In severe displaced 4 part fractures with no possibility to reconstruct the humeral head, a fracture prosthesis can be used. As the result of fracture prosthesis is often limited, the routine use of this type of treatment is not advised.
The shoulder consists of a ball (humeral head) and socket (glenoid). The ball is stabilized in the socket by a cartilage rim (labrum) and the ligaments, which attach to the labrum. Usually the shoulder dislocates to the front (anterior). For this to happen the arm is forced upwards, backwards and outwards (abduction and external rotation). Due to the levering of the humeral head onto the anterior side of the glenoid, the labrum, the ligaments, and sometimes a piece of bone, are pulled off the edge of the socket (Bankart lesion). As the head slips over the edge of the socket, the latter knocks a hole into the head (“Hill-Sachs” lesion).
A dislocation of the shoulder can be diagnosed clinically. The deformity of the shoulder is apparent by looking at it from the outside: the upper corner of the shoulder appears “squared off”, a bulge may be felt in front and a hollow at the back. Despite the clinical picture and the need for an immediate treatment, the taking of an X-ray of the shoulder is advised to diagnose associated fractures (especially the greater tuberosity). The acute situation of a shoulder dislocation is usually extremely painful and disabling. There is total inability to move the shoulder at this stage. Prompt reduction of the dislocation will result in pain relief and gain of mobility. An X-ray after the reduction is also relevant to verify that the shoulder is reduced after reduction maneuver.
A Bankart lesion (ligament and labrum tear) seldom heals and the shoulder dislocates repeatedly whenever the arm is forced upwards and outwards after the first dislocation. The younger the patient is at the time of the first dislocation, the more likely will he suffer recurrent dislocations (repeated episodes of the shoulder dislocation).
The reason is that in the young, the ligaments are so strong and elastic that they are stripped off the bone with the labrum, rather than tearing, and do not heal back to bone. The rate of recurrence in the under 25-year-old age group is 90-100%. As the shoulder dislocates repeatedly, progressively more damage is done, the bony lesions become larger, the ligaments stretch out and dislocations occur with greater ease.
Depending on the age of the patient, his or her involvement in contact or competition sport, hyperlaxity and the presence of a bony Bankart or Hill-Sachs lesion on the X-ray, one can decide on surgery and the type of surgery.
c) Surgical technique
Different open and arthroscopic surgical techniques exist in order to treat shoulder dislocations with or without bone loss. Nowadays the arthroscopic Bankart repair is the golden standard technique. It has the advantages of not harming he subscapularis muscle, which allows for a much faster rehabilitation and a reduction of the post-operative stiffness.
If there is bone loss on the glenoid, or a large Hill-Sachs lesion, the problem becomes more mechanical and will not be adequately treated by simply repairing the ligaments as in the Bankart procedure. In these situation a Latarjet procedure is the most appropriate treatment. The coracoid, with the attached conjoined tendon, is transferred through the subscapular muscle onto the glenoid. The sling effect of the transferred tendon which is attached to the coracoid also plays a major role in achieving stability. This is a highly successful procedure for those few cases that need it.
5. Rotator cuff tears
The muscles around the shoulder act to elevate the arm. The large outside muscle is the deltoid and deep to that is the rotator cuff – this is a combined tendon and inserts into a prominence on the humeral head known as the greater tuberosity. Four muscles contribute to the rotator cuff tendon: the supraspinatus, infraspinatus, teres minor and the subscapularis. Injuries (falls, etc.) can result in “traumatic” tears when a fall or another forceful mechanism tears the tendon off its insertion site. This can occur as an isolated lesion or combined with a shoulder dislocation. The most common muscle to tear is the supraspinatus muscle but case reports of subscapularis muscle tears as a result of bicycle accidents are reported. The management and treatment of rotator cuff tears after bicycle accidents is the same as for other traumatic rotator cuff tears. Arthroscopic repair is nowadays the gold standard procedure.
6. Scapular fractures
However very rare, scapular fractures do occur after bicycle accidents. Again these can be the consequence of a direct impact on the scapula or indirect as the consequence of a fall on an outstretched arm. Depending on the angle between the humerus and the glenoid plane at the moment of impact on the arm, different scenario’s can occur ranging from a shoulder dislocation over a glenoid fracture to a humeral head fracture. Depending on the type of glenoid fracture, the amount of communition and the involvement of the joint, one can decide to perfrom a surgical treatment (figure 7). Scapular blade fractures however are mostly treated conservatively and heal most of the time without any complications.
Figure 7: Open reduction and internal fixation of scapular neck fracture.