Bone Loss in Athletes

Fig. 7.1

(a) A large humeral head defect (Hill–Sachs lesion) is shown (G glenoid, H humeral defect). (b) A significant glenoid defect that resembles an “inverted-pear” glenoid is shown (G glenoid, H humeral head). (c) An “off-track” humeral head defect is seen engaging over a significant glenoid defect (G glenoid, H humeral head)

Glenoid defects occur most frequently at the anterior rim (2.30–4.30 o’clock) and can extend down to the 6 o’clock position on the anteroinferior rim [5]. Glenoid defects can be quantified reliably on preoperative imaging and intraoperative arthroscopic measurements, and a defect measuring 25% of the total glenoid width, or 19–21% of the glenoid length, is considered significant [6, 7]. Sugaya et al. [2] demonstrated “fragment (50%)” and “erosive (40%)” types of glenoid defects, while Bigliani et al. [8] reported 3 types of these lesions (avulsion fracture, medially malunited fracture, and erosive).

Humeral head defects (Hill–Sachs lesions) occur in 65–93% of anterior instability cases [9, 10]. The critical size of the humeral defect that is considered significant is unclear (4 cm length, 20–25% of humeral head surface, 250–1000 mm³ volume) [6, 11–14].

The concept of “engagement” was first put forth by Burkhart and De Beer, and they used dynamic air-arthroscopy to determine if the humeral head defect was an “engaging Hill–Sachs” lesion. Similarly, they used an antero-supero-lateral portal view to visualise and diagnose a significant “inverted-pear glenoid”, and described the bare spot as a landmark to quantify the glenoid defect [1, 15] (Fig. 7.1). Recently, Itoi et al. have described the concept of “Glenoid track” to assess bipolar bone loss. The glenoid track is defined as the “contact zone of the glenoid created on the humeral head along the end range of motion”; the medial margin of the glenoid track is located at a distance equivalent to 84% of the glenoid width in cadaveric shoulders and 83% in live shoulders [6, 7]. Based on this concept, Di Giacomo et al. [16] classified Hill–Sachs lesions as “on-track” and “off-track” Hill–Sachs lesions.

Glenoid bone loss in anterior instability may also be associated with soft tissue lesions. Arrigoni et al. [17] described associated pathological lesions in 73% of cases with significant bone loss. These included superior and posterior labral tears, loose bodies, rotator-cuff tears, and chondromalacia. The authors recommended arthroscopic evaluation prior to the surgical Latarjet procedure to treat these associated lesions. Bhatia and DasGupta [18] reported an 11% incidence of humeral avulsion of glenohumeral ligaments (HAGL) lesions in association with significant glenoid bone loss, and described a dual-window subscapularis-sparing approach to perform a combined Latarjet procedure and HAGL repair. Bernhardson et al. [19] have evaluated the association of an anterior labroligamentous periosteal sleeve avulsion (ALPSA) and glenoid bone loss; they found that “patients with anterior shoulder instability who have an ALPSA lesion have nearly twice the amount of glenoid bone loss as those with a standard Bankart tear (no ALPSA lesion)”.

7.4 Diagnosis

Significant bone loss should be suspected and evaluated in every athlete who presents with anterior shoulder instability. Clinical indicators of significant bone loss may be identified on history and physical examination, including; (1) frequent and easy dislocations, (2) dislocations in sleep, (3) high-energy traumatic dislocation, (4) failed previous stabilisation procedure, and (5) a positive “bony apprehension” test [20, 21].

Presence of associated lesions should be assessed on clinical examination, and tests for rotator cuff integrity, concomitant posterior instability, SLAP and biceps lesions, and acromioclavicular joint pathology should be performed.

Meticulous imaging is necessary to determine the extent of the labral tear and to quantify humeral and glenoid bone loss. Radiographic views (Table 7.1) that are useful in instability include; (1) a true anteroposterior view, (2) Garth view, (3) Bernageau view, and (4) Anteroposterior view with shoulder in external rotation [22, 23]

Table 7.1

Common radiographic views to assess glenoid and humeral bone loss

Radiographic view	Bone loss indicator
True anteroposterior view (Grashey view)	Positive LSGL sign (LSGL loss of anterior sclerotic glenoid line)
Apical oblique-45° caudal tilt view (Garth view)	Anteroinferior bone fragment visualised
Bernageau view	Inferior glenoid profile and Hill–Sachs visualised
Anteroposterior view with shoulder in external rotation	Significant Hill–Sachs visualised

Magnetic resonance imaging and MR arthrography show the bone lesion and associated soft tissue pathology (Labral tears, HAGL lesions, rotator-cuff tears, bone bruising, chondral lesions). Bone loss may also be quantified accurately by MRI, both plain and arthrographic [24]. CT scans are indicated for 3D reconstruction analysis of bone loss using one of several methods (Table 7.2) that have been described [2, 25–28] (Fig. 7.2)

Table 7.2

Common glenoid bone loss radiological measurement techniques

Bone-loss measurement method	Technique
Unilateral circle method (Chuang et al., Sugaya et al.)	A best-fit circle is drawn on 3D reconstruction of the inferior glenoid, and the defect is measured linearly (mm) or as area loss (mm²)
Bilateral Circle method (Pico Method, Baudi et al.)	Best-fit circle is drawn on inferior portion of the opposite normal glenoid and its surface area is digitally calculated This circle is superimposed onto the pathological glenoid, and surface area of defect is calculated
Bare area method (Sugaya et al.)	Bare area is approximated on computed tomography with use of intersecting lines, and distances are measured from bare area to anterior and posterior glenoid edges

Bone-loss measurement method

Technique

Unilateral circle method (Chuang et al., Sugaya et al.)

A best-fit circle is drawn on 3D reconstruction of the inferior glenoid, and the defect is measured linearly (mm) or as area loss (mm²)

Bilateral Circle method (Pico Method, Baudi et al.)

Best-fit circle is drawn on inferior portion of the opposite normal glenoid and its surface area is digitally calculated

This circle is superimposed onto the pathological glenoid, and surface area of defect is calculated

Bare area method (Sugaya et al.)

Bare area is approximated on computed tomography with use of intersecting lines, and distances are measured from bare area to anterior and posterior glenoid edges

../images/473070_1_En_7_Chapter/473070_1_En_7_Fig2_HTML.jpg — Fig. 7.2

Measurement of glenoid bone loss on 3D CT images using the circle method is shown. (a) shows the area loss, (b) shows the linear length loss of glenoid bone

Arthroscopic suspicion of glenoid bone loss is based on visualisation of an “inverted-pear” glenoid, and dynamic “air-arthroscopy” is useful to assess engagement in abduction and external rotation. Bone loss can be quantified with direct measurement using the bare spot as a reference [28, 29] (Fig. 7.3).

../images/473070_1_En_7_Chapter/473070_1_En_7_Fig3_HTML.jpg — Fig. 7.3

Arthroscopic evaluation of bone loss is demonstrated. The probe (M) first measures the linear distance between the anterior glenoid rim (ANT) and bare spot (B). This distance is then subtracted from the linear distance between the posterior glenoid rim (POST) and the bare spot, and this represents the glenoid bone loss

7.5 Management

Surgical treatment is recommended to treat bony instability, and the goal is to return the player to preinjury levels of overhead and contact sports. The decision making algorithm is broadly based on a combination of radiological quantification of bone loss, and the ISIS scoring system (Instability Severity Index Score) [29, 30]. Surgical techniques focus on preventing engagement of the humeral defect over the glenoid defect, and attempt to restore the glenoid track to normal (Table 7.3). This can be achieved using soft-tissue reconstruction (arthroscopic labroplasty ± remplissage), or by reconstructing the incomplete glenoid arc (Latarjet procedure, Iliac crest bone graft) [29, 31–40] (Figs. 7.4 and 7.5).

Table 7.3

Surgical procedures used by the authors to treat bony instability in athletes

Surgical techniques	Description
Labroplasty [29]	Sequential tensioning of the capsulolabral complex to recreate a labral bump at the anterior glenoid rim
Remplissage [31, 32]	Capsulotenodesis of infraspinatus and posterior capsule into the Hill-Sachs defect
Mini-open Latarjet procedure [33]	Coracoid process transfer along with the conjoint tendon to the anterior glenoid rim using a mini-open subscapularis split approach
Mini-open congruent arc Latarjet procedure [1, 34]	Coracoid process transfer along with the conjoint tendon to the anterior glenoid rim using a mini-open subscapularis split approach. The coracoid block is “flipped” to orient the inferior coracoid surface along the articular glenoid surface, and a capsular shift is added
Arthroscopic Latarjet [35]	Coracoid process transfer along with the conjoint tendon to the anterior glenoid rim using an arthroscopic approach
Arthroscopic Latarjet and Capsular Shift [36]	Coracoid process transfer along with the conjoint tendon to the anterior glenoid rim and capsular shift using an arthroscopic approach
Arthroscopic/open bone grafting [37, 38]	Bone grafting procedure using autograft iliac bone or osteochondral allograft (distal tibia)