Fig. 11.1
Beach-chair position of the patient with the arm draped free at the lateral edge of the table. Intraoperative reclination exposes the humeral head anterior to the acromion. Gravity helps in achieving and maintaining reduction by longitudinal traction
11.2.3 Surgical Approach and Fracture Reduction
Nailing of the proximal humerus is performed through an anterior acromial approach [39, 40]. Skin incision begins at the anterior edge of the acromion and is directed towards anterolateral and distal. The length of the approach is depending on the fracture type. In pure 2-part subcapital fractures, an incision with a length of approximately 3 cm is sufficient. The skin incision is extended towards distal by another 3–4 cm in more complex fracture situations where reduction and fixation of the tubercula is necessary [41].
The deltoid muscle is released 1–2 cm from the anterior margin of the acromion (Fig. 11.2a). It is refixed to the bone after the nailing procedure. An additional posterior extension of the approach can be achieved by detaching the muscle subperiostally from the acromion towards posterior on a length of 1–2 cm. Partial resection of the acromion is only exceptionally required for better access. The deltoid muscle is split from proximal to distal according to the direction of its fibres at the transition between its anterior and middle third. Care must be taken not to harm the axillary nerve [42, 43]. The nerve is located approximately 5 cm distal to the tip of the greater tubercle (Fig. 11.2b) [41, 44, 45]. At this level, it is running on the inner side of the deltoid muscle close to the bone [46]. Often, the nerve can be identified and localized by digital palpation.
Fig. 11.2
(a) The anterolateral edge of the acromion is a landmark for skin incision. The anterolateral approach can be extended by releasing the deltoid muscle subperiostally towards anterior and posterior on a distance of 1–2 cm in both directions. Appropriate exposure may be necessary in complex three- and four-part fractures in order to enable reduction of the tuberosities. (b) Anatomical view demonstrating the relationship between the axillary nerve and the humeral head. Splitting the deltoid muscle below the level of the axillary nerve is almost never required in nailing of proximal humeral fractures
In a first stage, indirect fracture reduction is attempted by longitudinal traction on the arm and by manipulation of the upper arm near to the fracture site. The same principles are applied as in indirect plate fixation [47]. Indirect reduction preserves the blood supply of the fracture fragments and avoids an enhanced risk of avascular necrosis. Persisting deformities in varus, valgus and/or retroversion of the humeral head fragment are reduced by its manipulation with a small elevator that is inserted through the main fracture line (see also Fig. 11.12c–d). Kirschner-wires with a diameter of 2.0 or 2.5 mm which are inserted into the head fragment may be used as “Joy-sticks”. These are very useful tools for reduction (Fig. 11.3). Two wires inserted in a distance of 1–2 cm from each other are more effective than one single wire. The wires should not block the insertion trajectory of the nail. In highly unstable fractures, K-wires exceptionally may be used for transient fixation of the humeral head against the glenoid. It is also important to achieve correct reduction and alignment between the humeral head and the shaft in both the anteroposterior and lateral planes. Alignment is a strong predictor of functional outcome [48].
Fig. 11.3
Two 2 mm K-wires are used for manipulating and reducing the head fragment. K-wires may also be used for keeping the greater tuberosity reduced against the head fragment. The position of the wires should not inhibit nail insertion. Additional holding sutures inserted through the rotator cuff tendon help reducing the tuberosities
Kralinger et al. highlighted the role of an intact posteromedial periosteal hinge for fracture reduction [49]. From the results of their biomechanical study, the authors concluded that an intact hinge is a mechanical structure capable of providing support for reduction by soft tissue distraction. The integrity of the medial hinge is also important form the biological point of view, since a disrupted hinge is a relevant predictor of ischemia [50].
Tuberosity fragments are manipulated and reduced with strong holding sutures that are inserted through the insertion of the rotator cuff to the bone. Sutures in this position are less likely to cut out than pure transosseous sutures. Pointed reduction clamps may be used additionally to achieve and maintain reduction.
It is important to notice that the correct entry portal of the nail can only be defined after correct alignment of the main fracture fragments. Especially the alignment between head and shaft fragment should be restored prior to opening of the entry portal. Once the entry portal is prepared, secondary corrections of reduction are difficult or impossible to obtain [51].
The supraspinatus tendon is split medial to its insertion on the greater tuberosity in line with its fibres. The incision has a length of approximately 2 cm [40]. Resorbable holding sutures or small retractors are used to protect the tendon and expose the humeral head (Fig. 11.4). Care must be taken not to harm the long biceps tendon, which normally runs slightly anterior to the tendon split. The entry portal for the nail gets easily accessible by proper reclination of the upper arm.
Fig. 11.4
Intraoperative view of a nailing procedure of the right proximal humerus. The supraspinatus tendon is incised under direct visual inspection according to the direction of its fibers. The two parts are subsequently retracted with holding sutures in order to avoid damage during implant insertion. The position of the ball-pointed guide rod depicts the correct entry portal
11.2.4 Nailing Procedure
11.2.4.1 Entry Point
The location of the optimal entry point is depending on the design of the nail. Curved nails will need a more lateral entry portal than straight nails. A correct entry portal is a prerequisite for a good reduction result [51]. The best entry portal for a straight nail is located posterior to the biceps tendon at the apex of the humeral head. This point is situated 1–1.5 cm medial to the insertion of the supraspinatus tendon. In curved nails, the ideal entry portal is located at the transition of the cartilage of the humeral head to the greater tubercle. The insertion of the supraspinatus tendon on the greater tubercle should not be damaged. Any incision of the supraspinatus tendon leads to a reduction of its capillary blood supply that however seems to be transient and reversible [52].
For straight nails, the correct entry portal in a reduced fracture situation is in line with the anatomic axis of the humeral diaphysis in both the anteroposterior and lateral plane (Fig. 11.5). The position and direction of the guide rod should be checked carefully in both planes and, if necessary, corrected prior to opening the entry portal. A common mistake is that the entry point is chosen too far lateral and/or anterior. This generally is due to insufficient reclination of the upper arm. A far lateral and/or anterior entry point inevitably causes persistent varus or retroversion and early secondary fracture displacement is a typical complication (Fig. 11.6a–c). Malreduction associated with a suboptimal starting point is very difficult to correct during the further course of the procedure.
Fig. 11.5
The correct entry point of the nail is defined after reduction of the head fragment against the shaft. In straight nails, it is in line with the axis of the humeral diaphysis in both planes. Correction at this stage is easily possible. Once the entry portal in the humeral head has been created, secondary attempts to correct implant position and improve fracture reduction are difficult – if not impossible – to realize
Fig. 11.6
Example of a good reduction in the a.p. projection with poor reduction in the lateral plane (a). Since retroversion had not been corrected in this two-part subcapital fracture, the entry portal of the nail as well as the position of the implant are too far anterior (b). Suboptimal reduction resulted in early failure of fixation (c)
Nails with a straight implant design have advantages that are both biological and biomechanical in nature in comparison with nails with a proximal bent [28]. This observation is related to the more lateral entry portal of bent nails. In general, a lateral entry point may cause damage to the insertion of the supraspinatus tendon at the greater tubercle, resulting in pain and/or deficiency of the rotator cuff. A lateral entry portal is also likely to enforce the nail to be inserted through the fracture gap between the humeral head and the greater tuberosity in 3- and 4-part fractures. Such a situation is less stable than a construct with an intact ring of dense cortical bone surrounding the proximal end of the nail. This area of intact dense bone is biomechanically important and serves as a “fifth” anchor point for proximal fixation (in addition to four proximal interlocking screws) [25, 28, 53]. The bending force on the proximal screws is shorter in straight nails as they pass through the nail more centrally in the head.
11.2.4.2 Nail Insertion
It is recommended to incise the tendon only after precise positioning of the guide wire which marks the centre of the entry portal, in order to avoid multiple incisions. A longitudinal incision is made through supraspinatus tendon at the position of the guide rod. Exposure of the entry portal at the humeral head is depicted in Fig. 11.4. Dependent upon the instrument set, either a canulated awl or a hollow drill is used to open the humeral head and medullary cavity. A protection sleeve is recommended to avoid damaging the rotator cuff. Even in manifest osteoporosis, the subchondral bone at the apex of the humeral head is dense; a nice cylinder of strong bone is nearly always removed with the hollow drill (Fig. 11.7a–c). The spongious bone surrounding the entry portal serves as an anchoring point in addition to head fixation screws. In order to adequately use this proximal anchoring point, the nail may not be inserted deeper than 2–3 mm below cartilage level. On the other hand, the proximal end of the nail must be inserted below cartilage level in order not to impinge under the acromion. The insertion depth of the nail therefore must be analyzed carefully by visual inspection and radiographically prior to locking. If necessary, correction of the insertion depth is required at this stage. Indentations on the insertion handle help to identify the position of the proximal end of the nail (Fig. 11.8).
Fig. 11.7
(a) Even in manifest osteoporosis, (b) the subchondral bone at the apex of the humeral head is dense; (c) a nice cylinder of strong bone is nearly always removed with the hollow drill
Fig. 11.8
Insertion depth of the nail is determined by the relationship between the superior edge of the humeral head and the proximal end of the nail as well as by the position of the ascending calcar screw. Be aware that the exact estimation of the implant position can only be assessed with correct radiological projections. Radiological evaluation with the arm in a reclination or elevation may lead to severe misinterpretation. The proximal nail end including end cap should be 2–3 mm below cartilage in order to provide adequate stability and avoid hardware impingement. The ideal position of the ascending screw is just above the level of the calcar
The diameter of the nail should be adapted to the diameter of the medullary cavity. Toggling of the implant in the humeral diaphysis reduces the stability of fixation. The implant is inserted manually into the humeral head using twisting motions and advanced distally across the fracture under image intensifier monitoring. Do not use a hammer to forward the implant distally. If the nail cannot be inserted manually, there usually is a mismatch between the diameter of the nail and the medullary cavity. In such a case, an implant with a smaller diameter should be chosen or – if not available – it is recommended to widen the medullary cavity with hand reamers. Lateral or medial displacement of the shaft in relation to the head is corrected by nail insertion as long as the entry portal has been chosen correctly. Once the nail is inserted, correction of varus, valgus or retroversion is not possible anymore unless a completely new entry portal is created.
11.2.4.3 Proximal Nail Interlocking
Proximal locking is typically done with an aiming arm, mounted on the insertion handle (Fig. 11.9). It is recommended to use at least three screws for the fixation of the head fragment. This is especially relevant in osteoporotic bone and in fractures with metaphyseal comminution. Do not perforate the articular surface during drilling in order to reduce the risk of screw tip penetration into the joint. Locking screws with blunt tips reduce the risk of penetration additionally.
Fig. 11.9
For proximal and distal locking, an aiming arm is mounted on the insertion handle. At least three screws should be used for proximal fixation. Two screws are recommended for distal locking in order to reduce the amount of toggling of the implant in the medullary canal
The rotation of the nail determines the position of the locking screws in the humeral head. Only with a correct nail rotation, optimal position of the proximal locking screws can be guaranteed. The retroversion of the head fragment of approximately 20° in relation to the shaft has also to be taken into account. Furthermore, correct nail rotation is important for preventing locking screws to be inserted through the long head of the biceps tendon, which runs in the intertubercular sulcus.
The tuberosities have to be reduced and provisionally fixed with holding sutures, K-wires or pointed reduction clamps prior to proximal locking. Large tuberosity fragments can be fixed directly with one or two proximal locking screws. Additionally, separate sutures are placed through the tendinous insertion of the supraspinatus, infraspinatus and subscapularis muscle. These sutures can be the same as or different from the sutures used for manipulation and reduction of the tuberosities. They are fixed to the proximal locking screws, using available suture holes in the screw head. Alternatively, they are tightened around the screw head.
In specific implants like the Multiloc nail, the stability of internal fixation can be improved by the use of an additional calcar screw [22]. This screw, that is inserted from lateral in an 135° ascending angle towards proximal medial, supports the inferomedial aspect of the humeral head and augments the stability of the medial buttress. This is especially relevant in fractures with medial metaphyseal comminution. Achieving an anatomic reduction or a slight impaction of the medial column is important for prevention of secondary varus displacement [11, 54].
Intramedullary nails– in contrast with plates – have the disadvantage that the direction and orientation of possible proximal locking screws is limited by the anatomy of the proximal humerus and dictated by the position of the nail inside. In a centrally placed nail, all screws necessarily need to converge to pass through the nail. When interlocking in multiple plains should be obtained, the screws must be inserted from different entry points situated anteriorly, laterally and posteriorly of the humeral head. The superior and the posteromedial quadrants of the humeral head have been identified with the highest bone mineral density [4]. These areas therefore are most appropriate for realizing stable implant anchorage with interlocking screws. However, it is impossible to place screws in this area when they have to pass through the nail. Directing any such screw towards posteromedial needs its insertion through the bicipital groove.
The Multiloc nail offers the option to insert additional 3.5 mm locking screws through the head of the primary screws (Fig. 11.10a, b). Thanks to this innovative “screw-in-screw” concept, these secondary screws do not pass a nail hole, but run dorsal to the nail in an angle of 30° in relation to the interlocking screws towards posteromedial [22]. They considerably increase the volume of the supported area of the humeral head and add to an overall improved biomechanical stability (Fig. 11.11a–f) [4, 55].
Fig. 11.10
(a) The Multiloc humeral nail allows the insertion of secondary screws (screw-in-screw-technique) in order to enhance the stability of proximal fixation. A centering sleeve, inserted in the head of the primary screw, is tilted 30° anteriorly. (b) Secondary screws pass posterior to the nail into the posteromedial quadrant of the humeral head. According to bone density studies, bone quality is superior in this area of the humeral head
Fig. 11.11
(a, b) Three-part fracture of the proximal humerus in a 72-year old male patient. Injury pattern is characterized by a varus displaced fracture at the level of the surgical neck in combination with a fracture of the greater tuberosity. (c, d) CT-scans demonstrate the varus instability with disrupted medial hinge. (e, f) Result at 1 year after surgical fixation with a Multiloc nail. A calcar screw has been used to support the medial column. The most distal of the three proximal interlocking screws and another screw-in-screw, which is inserted through the screw head of the most proximal interlocking screw, are directed towards the posteromedial quadrant. This is best visible in (f)
The indication for the use of secondary screws is dependent upon the fracture type, bone quality and degree of instability. The more unstable the fracture is and the poorer the bone quality, the more useful is the insertion of additional screws.
The use of screw-in-screw fixation should be documented in the operating protocol for later hardware removal, since the secondary screws are not always clearly visible on X-rays due to radiological overlap of implants (Fig. 11.11a–f).
11.2.4.4 Distal Locking and Termination of the Procedure
Distal locking should be done with at least two screws in order to avoid excessive toggling, especially in wide medullary cavities. Some implants provide the possibility to enhance stability by the use of angular stable screws. Angular stable screws require specific instruments for their insertion. These screws seem to have advantages in fracture situations, where an increased stability of fixation is required: fractures with extensive metaphyseal comminution as well as fractures with severe osteoporosis [56].
Subsequent to nail insertion and locking, an end cap is inserted into the proximal end of the nail. In cases where the nail is inserted deep into the bone, proximal extension of the nail is possible and recommended by the use of a longer end cap. Doing so, we take profit of the anchor point at the level of the subchondral bone which adds to the stability of the bone-implant construct. Care however must be taken that the proximal end of the nail does not protrude in the subacromial space in order to avoid implant related impingement.
The rotator cuff is meticulously adapted with resorbable sutures. A drain is not necessary when wounds are dry. The deltoid muscle is reattached to the acromion using strong 1.0 sutures.
11.3 Special Considerations
In young patients below the age of 35 years, antegrade nailing of proximal humerus fractures should be discussed critically, since the surgical approach through the subacromial bursa and the rotator cuff may affect shoulder function. Plate or minimally invasive fixation should be considered as alternative procedures.
Simple two-part subcapital fractures in old patients can be nailed percutaneously according to a minimally invasive procedure [57]. A skin incision of 2.0 cm is sufficient for nail insertion.
Fractures extending into the diaphysis as well as segmental fractures of the humeral head and diaphysis are preferably stabilised with a long nail. Occasionally, additional fixation with cerclage wires or sutures may be required in order to adapt and keep large butterfly fragments reduced.
11.4 Implant Removal
Nail removal is not recommended as a routine. As long as the nail is inserted correctly and does not impinge in the subacromial space or interfere with the rotator cuff, the indication for hardware removal is at most relative. The supraspinatus tendon mostly heals with no visible scar. The proximal end of the nail therefore is difficult to localise even when an image intensifier is used. The renewed approach through the rotator cuff may lead to new damage or additional scar formation and may be a source of complaints and shoulder disability.
Removal of specific interlocking screws should be considered (partial implant removal) in case of primary or secondary penetration of screw tips into the joint or in case the screw head is not flush with the bone and interferes with the acromion. The latter complication quite often is observed with older nail generations due to secondary backing out of screws during functional aftertreatment.
11.5 Postoperative Management
Early functional aftertreatment is recommended in order to avoid shoulder stiffness. Passive and active-assisted exercises should be started on the first or second postoperative day. Management however should be adapted to the estimated stability of the bone-implant construct and as such also depends on the initial fracture characteristics, bone quality and patient compliance. The use of an arm sling for the first 7–10 days is recommended. Abduction is limited to 60° for 1 weeks and to 90° until the 4th week. Weight bearing activities and sports are allowed after 3 months only. Conventional radiographs are made immediately postoperatively and at regular time intervals in order to document proper healing and detect potential loss of reduction.
11.6 Typical Complications and Common Mistakes
The final surgical result after intramedullary nailing of proximal humeral fractures not only depends on the fracture type, bone quality and patient compliance. The outcome is also significantly influenced by the quality of the surgical technique. Technical errors, pitfalls and hazards should be prevented whenever possible. Common surgery-related issues are:
Incomplete fracture reduction: especially persisting varus and/or displacement of the tuberosities affect outcome negatively. In selected patients, secondary correction osteotomy may be considered (see also Fig. 11.13) [10, 36].
Suboptimal entry point: When nailing is started without fracture reduction, there is a significant risk for choosing a wrong entry portal with malalignment as a consequence. Fracture reduction after nail insertion is nearly impossible to realize and may ultimately require plate and screw fixation. A too anterior and too lateral starting point is often observed. The position of the guide rod therefore should be checked meticulously in both radiographic planes before the nailing procedure is started.
Suboptimal cranio-caudal position of the nail in the humeral head: implants protruding in the subacromial space interfere with the rotator cuff, affect shoulder function and contribute to an unsatisfactory functional outcome. Early implant removal must be considered in such situations. Nails that are inserted too deep provide less stability since the “fifth” anchor point cannot be used and proximal locking screws are inserted too inferior. The insertion depth of the nail therefore must be checked in the exact anteroposterior radiographic projection prior to interlocking.
Unstable fixation: the use of at least three locking screws proximally and two screws distally is strongly recommended. The nail should have an appropriate diameter in relation to the width of the medullary cavity. The configuration of proximal interlocking should be adapted to the specific fracture situation taking into account that varus, medial metaphyseal comminution, multifragmentary and intra-articular fractures; and severe osteoporosis are relevant indicators of instability.
Intra-articular screw penetration may be a source of pain and can lead to wear and destruction of the articular glenoid surface. Screw perforation into the joint must be excluded intra-operatively with dynamic image intensifier control and requires immediate replacement by screws of an appropriate length. In cases where primary or secondary intra-articular screw perforation is detected postoperatively, removal or exchange by a shorter screw is recommended.
11.7 Outcome
11.7.1 Biomechanical Results
A few experimental studies compared plate fixation with intramedullary nailing under biomechanical conditions. In a two-part subcapital fracture with a medial defect simulating a medial metaphyseal comminution, two studies showed that intramedullary load carriers were biomechanically superior in comparison to plate fixation systems [58, 59]. In a three-part fracture, the angular stable Philos-plate was stiffer and showed a higher load to failure than a nail with a proximal spiral blade [59]. In another study however, superior results for the intramedullary implant were found [60]. Differences in outcome between those studies may be explained by the different experimental setup, because fracture models were different and nails differed for what concerned their type of proximal fixation [61]. Therefore, extrapolation of results from one nail type to another is not recommended. Dietz et al. assessed the biomechanical properties of a retrograde nail and found excellent results in comparison to plate fixation [62].
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