Arthroscopic fixation of a large glenoid fracture (Type 1b). (a) Direct visualization via the anterosuperior portal. (b) Cleaning of the fracture site using a shaver. (c) Improved visualization of the fracture line after removal of the hematoma. (d) Mobilization of the fracture fragment using an elevator. (e) Reduction attempts of the fracture fragment
(a) View of the fracture gap via the anterosuperior portal. (b) Insertion of a K-wire which helps to temporarily fix the fragment. (c) Position of the fragment after reduction. (d) Image of a resorbable screw used for fragment fixation. (e) Visualization of the reduced fracture. (f) Insertion of a knotless suture anchor to refix the labrum to the glenoid superior to the fragment
Accompanying labral defects may be addressed using suture anchors, as well [13, 16].
12.1.4 Results
Arthroscopic treatment of glenoid fractures shows excellent clinical and radiological results with healing of the glenoid fracture and restored stability in the majority of patients up to 2 years after the procedure [12, 13, 16, 18]. Accordingly, patient satisfaction and subjective shoulder scores were also considerably high [9, 12, 13, 16, 19]. While postoperative range of motion was excellent in most directions, several studies found a mild restriction of external rotation when compared to the uninjured side [13, 16, 18].
12.1.5 Complications
12.1.5.1 Pre-Operative/Indication
Preoperative evaluation of a glenoid fracture is essential in order to choose the right treatment strategy and to avoid possible complications associated with different techniques. Generally, glenoid fractures with a large fragment, gross displacement, or associated instability should be treated surgically [12]. More specifically, fractures with a large and solitary fracture fragment (Type Ib), a step formation of more than 2 mm, and without concomitant neurological injuries such as brachial plexus lesions are suitable for fixation with an arthroscopic screw osteosynthesis or osteochondral darts [13]. Fractures with smaller or multiple fragments (Type Ia or Type Ic) eventually require indirect fixation with a suture anchor system, because the size of the fracture fragments may not be large enough for screw fixation [15, 16].
12.1.5.2 Intra-Operative
One of the main reasons for intraoperative challenges and complications can be as simple as the lack of availability of instruments specifically dedicated to arthroscopic fracture fixation. If the K-wire drills or screw drivers are too short for arthroscopic use, a definitive fixation is impossible [17]. Another potential complication arises from the goal to insert screws perpendicularly to the fracture orientation. Fractures with an oblique direction are especially demanding to treat, because they might require a deep antero-inferior portal with risk of neurovascular injury [17]. In general, anterior and anteroinferior portals need to be carefully placed in order to avoid damage of relevant neurovascular structures including the axillary nerve, the cephalic vein, the musculocutaneous nerve, the brachial plexus, and the brachial artery [19]. The risk of axillary nerve damage is particularly high when placing the portal in a 5.00–5.30 o’clock position [20, 21]. A portal placed in a 3.00–4.00 o’clock position, on the other hand, bears less potential of neurovascular damage [21]. In addition, cannulas or percutaneous drill sleeves should be used to avoid any direct contact with relevant neurovascular structures.
In case metallic screws are used for fragment fixation, attention has to be paid to insert them almost parallel to the joint line and not too close to the articular surface in order to avoid mechanical impingement and damage to the cartilage of the humeral head which make screw removal necessary [13]. Also, it is recommended to tighten the screws with caution, because overtightening may lead to fragment comminution during fixation. A good alternative are screws or darts with a headless profile that can be inserted without being parallel to the joint line.
If fragments are temporarily reduced with K-wires and subsequently fixed indirectly with suture anchors by reattaching the labrum, care must be taken to avoid secondary medial displacement of the fragments after K-wire removal. When using the indirect fixation technique, it is advantageous to keep the labrum in continuity with the fragments attached, since indirect fixation might otherwise become very difficult. In case of highly comminuted free floating fragments, arthroscopic or even open fixation may become impossible and thus an intraoperative switch to an open or arthroscopic glenoid reconstruction procedure using a bone graft may become necessary [13].
12.1.5.3 Post-Operative
Hardware conflict with protruding screws in a 65 year old female patient. (a) Anteroposterior view. (b) Lateral view. (c) Axial view
Hardware conflict with protruding screws in a 65 year old female patient. (a) Coronal plane, (b) axial plane
12.2 Greater and Lesser Tuberosity Fractures
12.2.1 Introduction
The greater tuberosity (GT) is fractured in 13% to 33% of all proximal humeral fractures [22]. Despite their frequent occurrence, isolated fractures of the greater tuberosity are scarce and often a consequence of shoulder dislocations [23]. Depending on the mechanism of injury, GT-fractures can be divided into impaction fractures, avulsion/shearing injuries, and bony rotator cuff avulsions with only small bony fracture fragments. While impaction fractures most commonly result from a direct fall on the shoulder or a hyperabduction with impaction of the GT, avulsion or shearing injuries are associated with anterior shoulder dislocations and subsequent shearing off the GT by contact against the glenoid [3, 23, 24]. With the postero-superior parts of the rotator cuff being attached, the greater tuberosity is an integral and eminently important part for shoulder function and is therefore particularly sensitive to traumatic changes. Accordingly, a biomechanical study found even small amounts of GT fragment displacement to alter the balance of forces required to elevate the arm [25]. The already confined anatomical conditions in the subacromial space may further be narrowed by cranial displacement of the GT fracture fragment and subsequently lead to massive limitations of shoulder mobility and pain [26]. In order to avoid these adverse consequences, the indication for conservative or operative treatment must be closely evaluated. Open surgical approaches are associated with a higher morbidity due to the more invasive surgical approach involving splitting of the deltoid muscle. However, arthroscopic fracture treatment may be difficult in severely displaced fractures, multi-fragmentary fractures, or patients with poor bone quality and as a consequence, an open surgical approach may be preferred [26]. Isolated fractures of the lesser tuberosity with intact humeral head are rare injuries, predominantly affecting young males. A high energy abduction external rotation trauma with a bony avulsion of the lesser tuberosity is causative in most cases [27–30]. Similar to greater tuberosity fractures, even slight displacement of the lesser tuberosity can have a negative effect on functional outcome and therefore surgical treatment is the preferred method for patients with displaced avulsion fractures [28, 30, 31]. However, due to the rare incidence of this injury, there is no general rule which fractures need surgical treatment.
12.2.2 Surgical Technique
12.2.2.1 Greater Tuberosity Fractures
The patient is positioned in beach chair position [26, 32–34], which is preferred by the authors, or in lateral decubitus position [35, 36]. It is reasonable to perform a diagnostic arthroscopy not only focused on the footprint of the rotator cuff but also including the pulley system of the long biceps tendon [26], capsulo-ligamentous structures, labrum and cartilage, since greater tuberosity fractures are frequently accompanied by other injuries of the glenohumeral joint [23]. After debridement of the fracture site the arthroscope is moved to the subacromial space [35]. It may be useful to make the incision for the scope more superior and lateral to the classical posterior soft spot to allow a better vision of the greater tuberosity and the rotator cuff when inspecting the subacromial space [34]. Based on the underlying operative technique, several different tools and methods for fracture reduction have been introduced. The range extends from a blunt trochar [26, 34, 35], a probe hook [36], to a suture lasso device [32], or different arthroscopic retrieval devices.
After successful fracture reduction, K-wires [34, 37] or a forceps [37] may be beneficial to successfully maintain fracture reduction. In general, there are three different ways for arthroscopic refixation of a fractured greater tuberosity described in the literature.
In the beginning, cannulated screws were the method of choice [34, 37]. The screws are inserted over the K-wire and preferably aligned at an angle of 45° to the humeral diaphysis [37]. Although firm, compressive fixation of the tuberosity can be achieved with this approach [34], this technique is not ideal in multi-fragmentary fractures or patients with poor bone quality [26].
Arthroscopically assisted surgical treatment of a displaced isolated greater tuberosity fracture. (a) Arthroscopic intra-articular view of the displaced greater tuberosity fracture from a posterior portal. (b) Visualization of the fracture fragment from a lateral portal. (c) Insertion of a suture anchor on the medial aspect of the footprint. (d–f) Use of a suture passing device to pass all sutures through the rotator cuff medial to the bone fragment. (g) Lateral fixation of the sutures by inserting a knotless suture anchor distal to the fracture site. (h, i) Subacromial and intra-articular view of the successfully reduced fracture
12.2.2.2 Lesser Tuberosity Fractures
The patient is positioned in beach chair position and a diagnostic arthroscopy is performed with inspection of the subscapularis insertion zone including the long head of the biceps and the reflection pulley from superior to inferior. Visualization of the inferior parts of the subscapularis tendon can be achieved with further internal rotation of the arm. A mattress stitch formation is achieved anterior to the subscapularis tendon. For that purpose, two suture anchors are inserted into the fracture site. The threads are retrieved via the anterosuperior portal, thereby shuttling the sutures through the subscapularis tendon, which is perforated at the most inferior aspect adjacent to the bone-tendon-interface. The avulsed lesser tuberosity is reduced with a sliding knot. In addition to medial row suture anchor fixation, a second (lateral) row can be used to improve fixation.
12.2.3 Results
12.2.3.1 Greater Tuberosity Fractures
Results after screw fixation are scarce in the literature. However, there are various studies on techniques using suture anchor fixation. Postoperative pain level is low, especially when compared to the preoperative situation [36]. Patient reported outcome scores including the UCLA score [36], the ASES score [36], and the Subjective Shoulder Value [26] are comparatively high, indicating great patient satisfaction. Most patients also regained satisfying mobility including a mean abduction ranging from 153° to 157° [36].
12.2.3.2 Lesser Tuberosity Fractures
The available literature on arthroscopical treatment of isolated lesser tuberosity fractures is limited to case reports. However, in a case report, the Constant Score improved from 61.4 points to 91.3 points. The patient was completely pain free with a negative lift off test and a negative Napoleon/belly-press test. Radiographic evaluation revealed an anatomical consolidation of the lesser tuberosity [30].
12.2.4 Complications
12.2.4.1 Pre-Operative/Indication
In all cases it is necessary not only to consider the morphology of the fracture but also functional demands of the individual patient in order to determine the actual necessity for surgical intervention and justify its conveyed risks. Neer et al. proposed to only treat proximal humerus fractures with displacement of more than 1cm or 45° of angulation surgically [39]. However, as mentioned above, even small amounts of GT fragment displacement can alter the balance of forces required to elevate the arm [25] and further narrow the already confined subacromial space leading to massive limitations of shoulder mobility and pain [26]. Additionally, a study investigating epidemiological characteristics of proximal humeral fractures found major differences between isolated fractures of the greater tuberosity and proximal humeral fractures in general. More precisely, patients with isolated GT fractures were found to be comparatively young, predominantly male, and suffered from less comorbidities. Additionally, isolated greater tuberosity fractures were more frequently associated with traumatic shoulder dislocations [40]. Thus, the authors suggested to consider treatment and classification of isolated GT fractures separately from that for proximal humeral fractures in general [40]. The current recommendation is to treat greater tuberosity fractures with a displacement of more than 5 mm surgically [41]. In athletes and heavy laborers who are involved in overhead activity this threshold is lowered to 3 mm [42]. However, no randomized trials have confirmed these recommendations. Additionally, the chronicity of the fracture must be respected. There are no general recommendations for the surgical treatment of isolated lesser tuberosity fractures due to the rare occurrence of this injury.
12.2.4.2 Intra-Operative
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