Introduction
The treatment of proximal humerus fractures has undergone a large number of different concepts over the last years. Beside conservative measures, a variety of operative techniques have been pro- posed.
Decision-making is based on the specific frac- ture pattern, the quality of bone and the individu- al patient parameters such as biological age and functional needs.
Fractures with minimal or no displacement should usually be treated nonoperatively, as good functional outcome for this group of fractures has been reported [1]. Fortunately, 70±80% of all frac- tures of the humeral head can be treated conser- vatively, because they are not dislocated.
On the other hand, there is consensus that in displaced and highly comminuted four-part frac- tures and head-splitting fractures in the elderly, a primary hemiarthroplasty is recommended [2].
The treatment of displaced three-part and even four-part fractures of the proximal humerus re- mains controversial. The reported techniques show a wide range of different recommendations, such as percutaneous procedures using wires, pins or screws [3, 4], to open procedures with plate fixation or even joint replacement. The plate fixa- tion of proximal humeral fractures is due to the introduction of angular stable locking plates, and reports show a good outcome [5, 6]. Nevertheless, plate fixation often needs an extended exposure of the fracture elements and can increase the risk of osteonecrosis of the humeral head by disturb- ing the blood supply. Bulky extramedullary hard- ware can lead to mechanical complications, as subacromial impingement, and loosening of the plate and screws in poor bone stock have been re- ported.
Therefore, minimally invasive techniques with closed and indirect reduction have been advo- cated to preserve the soft tissue envelope and the blood supply to the humeral head and fracture elements.
Intramedullary nailing is a common and usual therapy in the treatment of humeral shaft frac- tures. In proximal fractures, using intramedullary implants is associated with problems of secure fixation and achieving a rotational stability of the humeral head and its fragments. Therefore, be- cause of the success of angular stable locking plates, angular and sliding stable locking nails have been developed [7±9].
These nails should provide multiplanar locking modes for a rigid fracture fixation, achieving a rotator cuff stability to allow early mobilization without the risk of secondary loss of reduction.
Cadaver analyses have shown that the highest bone strength can be found in medial and dorsal aspects of the humeral head and that it decreases from cranial to caudal [10]. Implants should therefore provide secure fixation in this area.
Indications
Common classification systems for fracture typing of the proximal humerus are those from Codman, the AO system and the Neer classification [11].
Although limited inter- and intraobserver reliabil- ity is reported [12, 13], the Neer classification still represents the most used typing system in clinical practice.
As shown in Fig. 4.10.2.1, Neer describes four major fragments: the humeral head, the lesser tu- berosity, the greater tuberosity and the humeral shaft. The classification is based on the presence or absence of significant displacement of one or more of these bone segments. If any of these frag- ments shows a displacement of more than 1 cm or is angulated more than 458, the fracture is said to be displaced.
According to Neer: ªDisplacement defined arbi- trarily as a guide for surgeons ± 1 cm or 45 de- grees, but no guarantee that those with less dis- placement will do well.º
One-part fractures are nondisplaced fractures or fractures with minimal displacement. A two-
Intramedullary Nailing of Proximal Humeral Fractures
A. Elsen
part fracture is one in which only a single seg- ment is displaced in relation to the other three.
Three-part fractures occur when two segments are displaced with relation to the other two parts and a four-part fracture exists when all the hum- eral segments are displaced. Computed tomogra- phy scans allow an accurate determination of the Neer fracture pattern, particularly when the hum- eral fractures are complex.
This classification is not meant as a numerical classification but rather as a concept that makes it possible to describe a fracture or fracture disloca- tion with standard terminology.
According to this classification, we recommend intramedullary nailing for the following types of fractures:
· Neer type III
· Neer type IV three-part
· Neer type V three-part.
Additional indications are even four-part fractures but only with an intact head fragment. Special
features of the T2 proximal humerus nail allow reliable fixation in the often poor cancellous bone, and additional fragments can be augmented by suture, using the locking screws as an anchor.
Proximal humeral fractures with diaphyseal ex- tension can be treated by using special versions of intramedullary nails with a long diaphyseal stem.
Furthermore we see an indication in very proxi- mal humeral shaft fractures, where standard lock- ing nails in retro- or antegrade technique do not achieve a secure fixation of the proximal locking screws in the humeral head.
Implant Features and Instruments
The following report is based on the use of the T2 proximal humerus nail (Stryker Trauma GmbH, Prof. Kçntscher-Strasse 1±5, 24332 Schæn- kirchen, Germany).
The proximal humerus nail is made from type II anodized titanium alloy (Ti6AL4V) with its known mechanical advantages and biocompatibil- ity. The material allows postoperative CT and MRI scans with minimized appearance of artifacts.
The nail has four proximal locking holes, thus enabling separate locking of fragments of the les- ser tuberosity, the greater tuberosity and the humeral head. The proximal holes in the nail are threaded and have a nylon bushing to prevent screw back-out. The proximal 5-mm locking screws are in consequence of this feature axial and sliding stable fixated in the nail. Therefore the combination of the nail and the proximal screws performs mechanically as one firm con- struction.
The proximal humerus nail is manufactured in different versions. The standard short nail has a length of 150 mm and can be obtained in a left and right version with asymmetric positioning of the proximal locking screws to reduce possible le- sions of the axillary nerve. Additionally long nails from 220 to 300 mm can be obtained for the left and right humerus to handle proximal humeral fractures with diaphyseal extension (Fig. 4.10.2.2).
All nails have a proximal 68 lateral bend.
In both the short and long nail versions, the positioning of the proximal locking screws is guided by a target device. The distal locking for the short nail is done using the target device, whereas in the long nails a freehand locking is performed. The distal locking hole configuration allows either static or dynamic locking modes.
Proximal locking is always done using 5-mm screws; distal locking is performed with 4-mm
170 A. Elsen
Fig. 4.10.2.1.Neer classification
screws. For both diameters, a 3.5-mm drill is used.
Additional to the screw fixation a supplemen- tary hold in the humeral head is achieved by opti- mal fitting of the proximal nail end in the cortex.
Therefore end caps of three different heights in 2- mm increments allow fine adjustment to the length of the nail and optimize the purchase of the nail in the entrance hole.
All nails have a proximal diameter of 10 mm, distal 8 mm. The long nails are cannulated and al- low reaming of the medullary canal over a guide wire. The solid nail design of the short nail does not require additional reaming for nail insertion.
Most of the instruments are known from the T2 platform.
A specially designed carbon-fiber radiolucent targeting device (Fig. 4.10.2.3) allows placement of all proximal screws and distal locking screws of the short nail.
As described below in the operative technique, different features to secure the correct rotational alignment or the correct insertion depth of the nail are implemented in the target device.
Calibrated drill bits give correct measurements of screw length. Proximal screw holes should be drilled manually. This improves the surgeon's ªfeelº of the bone and helps to avoid penetration of the articular surface of the humeral head. The drill sleeves are held in position by a special fric- tion locking mechanism. These sleeves, when
locked into the targeting device, will also help to stabilize the nail and may temporarily stabilize fragments during fixation.
Operative Technique
The most important step before starting surgery is an accurate analysis of the fracture type and pattern. We therefore perform a CT scan in cases where classification with standard radiographic methods is uncertain or in complex fracture pat- terns.
We recommend placement of the patient in the ªbeach chairº position or supine on a radiolucent table supplemented with a standard arm rest.
Prior to disinfection and draping, the correct placement of the patient should be checked to en- sure that intraoperative fluoroscopy and access to entry side is possible (Fig. 4.10.2.4).
The skin incision should begin anterolateral to the acromion in line with the fibers of the deltoid muscle. The length of the incision depends on the fracture type and the need for an open reduction.
The deltoid muscle is split to expose the subdel- toid bursa; the supraspinatus tendon is then in- cised in line with its fibers after identification of the bicipital groove by palpation. Reduction of the fracture can often be realized in ªjoy stick
Fig. 4.10.2.2.T2 Proximal humerus nail
Fig. 4.10.2.3.Target device
techniqueº using a 2.5-mm Kirschner wire to ma- nipulate the fragments. As an alternative, sutures in the rotator cuff are used to achieve a valgus po- sition of the humeral head fragment. Temporary fixation of fragments in four-part fractures can be realized with 1.5-mm Kirschner wires. If closed reduction is not possible, an open reduction should be performed.
The T2 proximal humeral nail should be in- serted through a central entry point (Fig.
4.10.2.5). This entry point is located at the very top of the humeral head, in the articular surface, in line with the humeral axis. We would recom- mend this central access because of the supple- mentary hold of the nail in the cortex of the hum- eral head. An intermittently described lateral en- try point is located just inside the greater tuber- osity and aligned with the humeral axis. Apart from the decreased stability, in undislocated frac- tures of the greater tuberosity we have seen dislo-
cation of fragments when introducing the nail through the lateral entry point.
Identifying the correct entry point in align- ment with the humeral axis is the central step in the operative procedure. Control by digital palpa- tion of the long biceps tendon and the circumfer- ence of the humeral head, followed by fluoro- scopic verification in two planes, confirms the correct entry point before placing the guide wire.
Preparation of the entry point should be per- formed with a 10-mm hollow reamer to define a clear-cut portal. A 10-mm awl or a rigid reamer may comminute the cancellous structures and weaken the purchase of the nail in the subchon- dral bone. For reamed techniques a guide wire is inserted across the fracture site.
Further reaming is not necessary with the short version of the proximal humerus nail. The nail may be inserted directly. As it is not cannu- lated, the guide wire has to be removed first.
For insertion of the long nail, reaming of the medullary canal may be necessary. Reaming is commenced in 0.5-mm increments. Final reaming should be 1±1.5 mm larger than the diameter of the nail to be used. An unreamed technique can be considered in cases where the medullary canal has the appropriate diameter. In these cases, the long nail can be introduced directly over the guide wire.
As the arrangement of the proximal locking screws is asymmetrical for the right and left ver- sion, the appropriate nail is chosen and mounted to the targeting device. Before inserting the nail, correct alignment should be checked by inserting a drill or K wire through the required holes of the targeting device.
The nail should be inserted only with manual pressure. Using a hammer may result in addi- tional fractures or fragment displacements. If the nail does not advance easily, fluoroscopy should be used to identify the problem.
Depth of nail insertion may be determined with the help of two circumferential grooves on the nail adapter, which can be visualized with the image intensifier. The nail should be inserted at least up to the first groove on the adapter but not deeper than the second groove. Another option to determine nail insertion depth is performed with the target device. An inserted K wire (Fig.
4.10.2.3) indicates the exact top end of the nail.
Before proximal locking, the correct rotational position is checked. To achieve the correct ana- tomical 308 retroversion of the humeral head, a K wire is inserted through the targeting device. The wire should be parallel to the forearm to indicate the correct rotational alignment (Fig. 4.10.2.6).
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Fig. 4.10.2.4.Patient positioning
Fig. 4.10.2.5.Entry point
Except for the anteroposterior (AP) locking, all the proximal and distal locking procedures (short nail only) can be performed without changing the position of the targeting arm. Using sleeves in- serted in the target device, manually drilling with a 3.5-mm drill is performed until it is in contact with the subchondral bone. The far cortex should not be injured. The correct screw length may be read directly off the drill at the end of the drill sleeve. The 5.0-mm screws are available from 25 mm to 60 mm in 2.5-mm steps. If in doubt about the appropriate screw length, the next shorter one should be used to minimize the risk of penetrating the articular surface (Fig. 4.10.2.7).
The length of the locking screws should be checked with fluoroscopy. The next two screws are inserted in the same way using the target de- vice (Fig. 4.10.2.8).
The AP screw is designed to fix the lesser tu- berosity. To place this screw, the target device must be rotated (Fig. 4.10.2.9). After releasing the holding nut, the arm is pulled up and rotated anteriorly around the nail adapter.
We would recommend use of proximal locking options to achieve a secure fixation of the nail in
Fig. 4.10.2.6.Rotational alignment
Fig. 4.10.2.7.Proximal locking I
Fig. 4.10.2.8.Proximal locking II
Fig. 4.10.2.9.AP locking
the humeral head and in consequence safe frag- ment fixation. Fractures of the tubercles can be fixed with the locking screws in cases with good bone structure. In a situation with comminuted fragments of the tubercles, tension band sutures fixed at the screw heads can provide further sta- bility.
The distal locking with 4-mm screws can be done in static or dynamic mode. For static lock- ing mode, two distal locking screws are used (Fig.
4.10.2.10). Dynamic locking is done with one screw at the bottom of the oblong hole.
The target device cannot be used directly for distal locking of the long nail versions. But leav- ing the targeting device attached can facilitate the freehand locking procedure. A K wire placed through the targeting device is in the same plane as the AP locking holes at the nail tip, whereas the plane of the targeting arm is the same for the distal oblique holes (Fig. 4.10.2.11).
There are multiple locking techniques reported.
The critical step with any freehand locking tech- nique is to visualize a perfectly round locking hole with the C-arm. We recommend using an an- gulated radiolucent power drill under fluoroscopy.
In order to avoid lesions of neurovascular struc- tures, the limited open approach is preferable to stab incisions.
Similar to the short version, the long nail should be locked distally with at least two fully threaded 4-mm screws.
After distal locking, an end cap should be in- serted to adjust the height of the nail for optimal purchase in the subchondral bone. Additionally, the end cap locks and stabilizes the proximal locking screw. The length of the end cap must be selected accurately from three sizes (standard, +2 mm, +4 mm) to avoid subacromial impinge- ment.
Clinical Cases
The first case is a 65-year-old woman with a three-part fracture of the right proximal humerus (Figs. 4.10.2.12 and 4.10.2.13). A closed reduction and osteosynthesis with the T2 proximal humeral nail was performed (Figs. 4.10.2.14 and 4.10.2.15).
Nine months after primary surgery, the nail was removed (Figs. 4.10.2.16 and 4.10.2.17). Before re- moval of the implant, the patient showed a good clinical result and respectable range of motion (Figs. 4.10.2.18 and 4.10.2.19).
The second report is an 86-year-old male pa- tient with a two-part fracture of the humeral head with a diaphyseal extension of fracture lines (Figs.
174 A. Elsen
Fig. 4.10.2.10.Distal locking I
Fig. 4.10.2.11.Distal locking II
4.10.2.20 and 4.10.2.21). Stabilization was achieved with a long version of the T2 proximal humerus nail (Fig. 4.10.2.22). The patient underwent pri- mary surgery at the time of finishing this chapter, in January 2005. Therefore no further radiological images are available.
Fig. 4.10.2.12.Three-part fracture of the right proximal hu- merus
Fig. 4.10.2.13.Three-part fracture of the right proximal hu- merus
Fig. 4.10.2.14.Closed reduction and osteosynthesis with the T2 proximal humeral nail
Fig. 4.10.2.15.Closed reduction and osteosynthesis with the T2 proximal humeral nail
176 A. Elsen
Fig. 4.10.2.16.
The nail was re- moved 9 months after primary surgery
Fig. 4.10.2.17.
The nail was re- moved 9 months after primary surgery
Fig. 4.10.2.18.Good clinical result and range of motion be- fore removal of the implant
Fig. 4.10.2.19.Good clinical result and range of motion be- fore removal of the implant
Fig. 4.10.2.20.Two-part fracture of the humeral head with a diaphyseal extension of fracture lines
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Fig. 4.10.2.21.Two-part fracture of the humeral head with a diaphyseal extension of fracture lines
Fig. 4.10.2.22.Stabilization was achieved with a long version of the T2 proximal humeral nail
