En ortopedia, la lesión de Bankart es una rotura de la parte anteroinferior del reborde glenoideo o labrum glenoideo de la escápula, a consecuencia de una luxación anterior de hombro. Perthes lesion is variant of Bankart lesion, presenting as an anterior glenohumeral injury that occurs when the scapular periosteum remains intact but is stripped. Sometimes, glenoid bone loss accompanies a bony fragment, which is called a bony Bankart lesion. This is observed in.
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The basic concept of shoulder stability is explained in the first section of this article so that the following explanation of bony stability will be better and more easily understood by the readers. The shoulder joint is a ball-and-socket joint. Since the socket glenoid covers only one-quarter of the surface of the ball humeral head1 it has the greatest range of movement of all the joints in the body.
The track of the extended arm moved along the end-range creates a large circle around the shoulder joint. At the end-range of movement, a part of the shoulder capsule is tight, which prevents a translation of the humeral head on the glenoid socket.
This translation of the humeral head is called laxity. The anterior and posterior drawer tests load and shift test and sulcus test are performed with the arm in the mid-range of movement because these tests are aimed to detect the laxity of the shoulder joint.
‘On-track’ and ‘off-track’ shoulder lesions
Mid-range stability is provided by the negative intra-articular pressure 34 and the concavity-compression effect. This creates a negative intra-articular pressure, which sucks the humeral head into the glenoid socket and prevents a downward translation of the humeral head.
If the jombro is pulled downward sulcus testthe humeral head may translate inferiorly in varying degrees. In general, the negative value of the intra-articular pressure increases linearly with an increase of downward pull.
The responsiveness of intra-articular pressure to the external load is determined by the volume of the joint as well as the thickness and quality of the surrounding soft-tissue envelope, such as the joint capsule bankrat the muscles.
Some people may be able to subluxate or even dislocate the shoulder in the mid-range of movement due to a great amount of laxity. If this subluxation or dislocation accompanies no symptoms, this laxity is just physiological and no treatment is necessary. As soon as bankarrt muscle lesiin occurs with the arm elevated, the contraction force by the shoulder muscles pulls the humeral head against the glenoid socket, which in turn creates a resistance force against translation of the humeral head.
This stabilising mechanism is called a concavity-compression effect.
The glenoid socket is twice as deep in the superior-inferior direction as in the anteroposterior AP direction. The magnitude and direction of the resultant force by the ldsion muscles depend on the activity and position of the arm. Whatever the magnitude and direction, the perpendicular component of the resultant force against the glenoid socket multiplied by the stability ratio determines the resistance force.
At the end-range of movement, a part of the shoulder joint capsule becomes tight and prevents further movement of the arm. For example, the anteroinferior capsule including the inferior glenohumeral ligament IGHL becomes tight when the arm is in abduction, external rotation and horizontal extension.
The tight capsulo-ligamentous structure functions as a stabiliser of the humeral head in the direction of the tight capsule.
This is a traumatic shoulder dislocation, which is pathological and needs to be treated.
Perthes lesion – Wikipedia
Therefore, a dislocation could be physiological or pathological depending on which position of the arm the dislocation occurs in and whether it is accompanied by symptoms. What is wrong with a glenoid bony defect? It is a very fundamental question. When we first paid attention to this issue, there had been no quantitative biomechanical studies. It had been said that a bony defect of one-third of the glenoid or greater needs to be treated.
No-one can tell precisely what one-third of the glenoid is. As long as we use the subjective assessment, such as one-third or one-quarter, we will never be able to determine the critical size of a defect which needs to be treated.
This was the very beginning of our serial studies of shoulder stability related to the glenoid and humeral head defects. This was because in this position, the repaired anteroinferior capsule became tight and prevented the anterior translation of the humeral head, even with a large glenoid defect Fig.
However, once the arm came into the mid-range of movement, the head easily translated anteroinferiorly with a certain size of glenoid defect because there was no more protection by the tight capsule, and the glenoid socket was too leesion to keep the humeral head in jombro socket Fig.
These findings clearly tell us that the glenoid bony defect is related to the mid-range instability, not to the end-range instability. Bony defects created anteroinferiorly. Anteroinferior bony defects were created at the 4: The anterior capsule is tight; b with a large glenoid bony defect arrowthe bankwrt stability is still well preserved after the Bankart repair because the repaired capsule is tight and prevents the anterior translation of the humeral head.
After this study, we determined the precise location of the glenoid bony defect using 3D CT. However, due to the anterior oesion of the scapula, the direction of humeral head dislocation relative to the scapula was almost anterior 3: We repeated the similar biomechanical studies with a bony defect created in the anterior portion of the glenoid Fig.
First, we measured the bony stability using the stability ratio without any soft-tissue contribution; 13 next, we measured the shoulder stability after the Bankart repair in a displacement control study. The head dislocates anteroinferiorly relative to the trunk, but anteriorly relative to the scapula. Bony defects created anteriorly.
Anterior bony defects were created at 3: For the former, there are two methods: In that case, a best-fit circle method can be used instead.
For the latter, there are also two methods to express the defect size: Most people prefer to use the linear measurement Fig. All that is needed is a ruler.
‘On-track’ and ‘off-track’ shoulder lesions
A best-fit circle is applied, which fits perfectly to the posterior and to the inferior part of the glenoid. This circle is considered to be close to the original shape of the glenoid. The HSL is also commonly observed in shoulders with anterior instability. It is located at the posterior aspect of the humeral head, extending from 0 mm to 24 mm from the top of the head.
A HSL which is small and narrow but is located medially needs special attention in selecting an optimum treatment option Fig. This lesion is located close to the greater tuberosity. Hill-Sachs lesion HSL located medially: A HSL is not related to the mid-range stability because it is located away from the glenoid in the mid-range of movement Fig.
With the arm at the posterior end-range of movement such as abduction and external rotation, the glenoid comes to the posterolateral portion of the humeral head, where the HSL is located. If the HSL is entirely covered by the glenoid in this arm position, it cannot cause any instability Fig. However, if it is out of the glenoid coverage, it may engage with the anterior rim of the glenoid and cause a dislocation Fig. Thus, different from a glenoid bony defect, a HSL is related to the end-range instability.
Hill-Sachs lesion HSL in the mid-range: Hill-Sachs lesion HSL entirely covered by the glenoid at the end-range: Hill-Sachs lesion HSL not entirely covered by the glenoid at the end-range: How can we assess the risk of instability caused by a HSL?
What is the critical size of HSL? As mentioned previously, HSL is related to the end-range instability. There are two methods to assess the risk of HSL. One method is dynamic examination. During arthroscopic surgery, the relative relationship between the HSL and the glenoid can be assessed. It does not matter if the HSL engages with the glenoid before the Bankart repair; what we would like to know is whether there is a remnant risk of engagement afterwards.
This is the one and only purpose of carrying out the dynamic examination. Therefore, it should be performed after the Bankart repair. Unfortunately, most investigators perform the dynamic examination before the Bankart repair and call it an engaging HSL if this examination is positive. This is not the correct way to determine an engaging HSL and the prevalence was definitely overestimated. Parke et al 35 evaluated engagement before and after the Bankart repair.
In their series of shoulder stabilisations, 70 shoulders showed an engagement during dynamic examination after the Bankart repair and they added remplissage in these cases. The disadvantage of this method is that there is a risk of damaging the repair during the dynamic examination.
Hill-Sachs lesion HSL and the glenoid: Therefore, this is a stable shoulder; b the HSL is the same size as in abut it is not entirely covered by the glenoid due to a bony defect of the glenoid.
Thus, this shoulder is unstable. Dynamic examination before the Lseion repair: Dynamic lseion after the Bankart repair: The risk of HSL being engaged with the anterior rim of the glenoid becomes greatest when the arm is at the posterior end-range of movement because it is in this position that the glenoid overrides the HSL. For the purpose of assessing the risk kesion HSL relative to the glenoid, the glenoid track concept was introduced.
However, if it goes out of the glenoid track, the anterior rim of the glenoid may fall into the HSL, causing bnkart new dislocation. Reproduced with permission from Itoi E, Yamamoto N. Current Orthop Practice ; In our daily practice, we use en face views of both glenoids and the posterior view of the involved humeral head on 3D CT.
We apply this width 0. If the medial margin of the HSL stays within the glenoid track, there is no risk that this HSL engages with the anterior lewion of the glenoid. If the HSL extends more medially over the medial margin of the glenoid track, there is a risk of engagement. However, as described above, these terms are almost always misused and cause a lot of confusion.
Shoulder MR – Instability
In order to avoid this confusion, we proposed a new terminology: If the HSL is out of the glenoid track off-track lesionthere is a risk of engagement and dislocation. Drawing of the glenoid track: Locher et al 39 retrospectively analysed patients who underwent arthroscopic Bankart repair. The odds ratio of off-track patients over the on-track patients to experience bankadt was 8.
Shaha et al 40 also looked at 57 lsion who underwent arthroscopic Bankart repair.