Intramedullary Nailing of Humeral Shaft Fractures J. Franke

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Introduction

For the treatment of humeral shaft fractures, conservative treatment still competes with the operative approach to a much greater degree than is the case for fractures of the long bones of the lower extremity. The trend toward operative treatment continues unabated, however. Whereas Lo- renz Bæhler [4] could still write an article with the title ªGegen die operative Behandlung von frischen Oberarmschaftbrçchenº [Against the operative treatment of fresh humeral shaft fractures]

in 1964, conservative treatment of humeral shaft fractures is now the exception at many hospitals.

There are three main reasons for the preference now given to operative methods for the treatment of humeral shaft fractures: (1) the frequent ab- sence of the necessary prerequisites for successful conservative therapy; (2) preferences expressed by patients; (3) the inherent advantages of surgical treatment as well as recent advances in surgical treatment (in particular, intramedullary osteosynthesis).

Indications

Assuming good patient compliance, an uncomplicated fracture of the humeral shaft represents an ideal indication for conservative treatment with the Sarmiento upper arm brace [12]. There are a number of situations, however, in which surgical treatment is required or in which an operative approach offers distinct advantages. In recent years, patient preferences ± and the increasing de- mands that patients be rehabilitated quickly so they can return to work sooner ± have played an increasing role.

For all of these reasons, the range of indications for osteosynthesis via intramedullary nailing has expanded markedly in recent years. In comparison with plate fixation, intramedullary nailing offers all the advantages of intramedullary im-

plants for the treatment of humeral shaft fractures. The most important of these are: minimal surgical trauma, biological osteosynthesis, high stability of osteosynthesis, and short operation times [2, 5].

The classical indications for surgical treatment of humeral shaft fractures (Table 4.10.3.1) are quite naturally also ideal indications for intramedullary nailing.

Patients with multiple trauma profit primarily from the stabilization achieved by intramedullary nailing. Biomechanical studies have shown that the central load-bearing element in the humerus can withstand higher loads ± such as those caused by the use of lower arm crutches ± than fractures stabilized via plate fixation [5]. This can be a de- cisive advantage during follow-up treatment in patients with concomitant injuries of the lower extremity.

Two additional advantages of intramedullary nailing are that it is a rapid surgical method with minimal soft-tissue damage and thus less blood loss.

Primary treatment of open fractures of grades I±

II8 can be achieved via humeral shaft nailing. For higher-grade open fractures, intramedullary nailing can be carried out following initial treatment with an external fixation device. The advantage of intramedullary nailing in this situation is that it in- volves less soft-tissue trauma than plate fixation.

Fractures involving injury to nerves and/or blood vessels can be stabilized via intramedullary nailing without causing any substantial additional soft-tissue trauma in the area around the fracture.

Intramedullary Nailing of Humeral Shaft Fractures

J. Franke

Table 4.10.3.1. Classical indications for operative treatment of humeral shaft fractures

Multiple trauma Open fractures

Nerve or vascular injury Chain injury, bilateral fractures Two-level fractures

Pathological fractures

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The high stability of the intramedullary implant provides secure protection of the reconstructed blood vessels. Multilevel fractures can be treated by intramedullary nailing without the necessity of a long incision. Special reduction tools (Fig.

4.10.3.7) make it easier to rejoin the bone fragments.

The humeral diaphysis is frequently the loca- tion of pathological fractures. These fractures are usually caused by osteoclastic metastases of primary tumors in the kidneys, lungs or breasts.

Fracture stabilization by intramedullary nailing represents an ideal method within the framework of (usually palliative) therapy [11]. The same ap- plies, of course, to the prophylactic stabilization of impending fractures.

In addition to these classical indications, there are a number of relative indications for which intramedullary nailing is especially suitable.

Transverse fractures and short oblique fractures of the humerus are a risk factor for the develop- ment of pseudarthrosis. A high degree of rotational stability is achieved when these fractures are treated via intramedullary nailing. The fracture apposition or compression achieved by intramedullary nailing offers additional possibilities for the improvement of fracture healing in this situation.

As a rule, pseudarthrosis is still a classical indication for plate fixation in combination with spongioplasty. In cases where pseudarthrosis has developed after conservative therapy (with the exception of atrophic pseudarthrosis), fracture con- solidation can be achieved by reamed intramedullary nailing. In this situation the reaming of the medullary canal serves as a kind of ªinternal spongioplasty.º For certain types of fractures, the possibility of fragment compression offered by the intramedullary nail represents an additional advantage of this technique. In the literature good outcomes have been reported for the combination of intramedullary nailing and spongioplasty as a treatment for pseudarthrosis [9, 10].

Correction osteotomies are rarely indicated in the humerus. Intramedullary nailing represents an ideal technique for osteotomy stabilization, e.g.

following derotation osteotomy.

Procedure Selection

Antegrade and retrograde procedures are basically equally suitable for the treatment of humeral shaft fractures. It is hard to decide which method is preferable since each of them has its own particular advantages and disadvantages. The following discussion has been provided to help the physi-

cian select the method most suitable for the particular case.

Implants and Instruments

The techniques described in this article are based on the use of the T2 humerus intramedullary nail system made by Stryker Howmedica GmbH (Fig.

4.10.3.1). This system is equally suitable for antegrade and retrograde intramedullary nailing. The nails are available in diameters of 7, 8 and 9 mm and lengths of 140±320 mm. To facilitate insertion and adaptation to anatomical configurations, the implants have a proximal curvature of 68 and a distal curvature of 48. This permits eccentric insertion of the nail into the humeral head from proximal during antegrade procedures and gentle insertion into the distal humerus during retrograde procedures. The nails are manufactured from a type II anodized titanium alloy (Ti6AL4V) and cannulated. Locking is carried out with 4.0- mm fully threaded locking screws and partially

Fig. 4.10.3.1.T2 humerus intramedullary nail for antegrade and retrograde intramedullary nailing

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threaded locking screws (shaft screws). Compres- sion locking can be carried out with the T2 compression screw (Fig. 4.10.3.2). End caps in various lengths and washers complete the system (Fig.

4.10.3.3).

Antegrade Intramedullary Nailing

During antegrade intramedullary nailing of the humerus, the intramedullary nail is inserted from

proximal toward distal (Fig. 4.10.3.4). The operative access is created via a deltoid split and incision of the rotator cuff. The negative effects on shoulder joint function associated with this access are sometimes considered a disadvantage of this method [1, 8, 13]. However, a search of the literature uncovers articles that report no difference in shoulder function following antegrade intramed-

Fig. 4.10.3.2. From left to right: T2 humerus compression screw (diameter 6 mm), fully threaded locking screw (diameter 4.0 mm), partially threaded locking screw (shaft screw) (diameter 4 mm)

Fig. 4.10.3.3.End caps for the T2 nail in various lengths

Fig. 4.10.3.4. Antegrade intramedullary nailing of the humerus with proximal diagonal locking

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ullary nailing in comparison with a retrograde approach or plate osteosynthesis [2, 7].

At our hospital the antegrade procedure is performed most frequently because it offers several technical advantages: patient positioning is sim- pler and the nail can be inserted more easily and with fewer complications. Reduction and rotation can be checked without any difficulty. Distal locking can be performed more easily via a ªfreehand techniqueº because of the better possibilities for radiological visualization. On the other hand, finding the correct nail entry point can be more difficult, owing to the small incision.

Fractures of the proximal humeral shaft ex- tending into the humeral head can be treated ef- fectively via antegrade intramedullary nailing by using long versions of the proximal humeral intramedullary nail with locking options ensuring angular stability (Fig. 4.10.3.5).

Positioning

The patient is placed in the ªbeach chair posi- tionº (Fig. 4.10.3.6), i.e. in a semi-reclining position, on the shoulder table, and the image intensifier is placed so that the humeral head can be vi-

sualized during the procedure. The patient's head is fixed in place on a head rest; cushions are placed under his/her knees and heels. X-ray control, which can be carried out without any difficulty, should be tested before the start of the operation. Special care should be exercised here that the entry point of the intramedullary nail in the humeral head can be visualized. The image intensifier is placed over the surgical field from the direction of the patient's head.

Access and Entry Point

A continuous skin incision is made from the ven- tral edge of the acromion toward lateral. After splitting the fibers of the deltoid muscle and ex- posing the subdeltoid bursa, the surgeon makes an incision into the supraspinatus tendon. The correct entry point at the tip of the greater tuber- cle about 1 cm dorsal to the long biceps tendon can now be easily palpated. It is wise to check the chosen entry point via the image intensifier.

The medullary canal in the humeral head is opened with a cannulated awl, which can be advanced up to the zone of transition between the metaphysis and the diaphysis. Alternatively, the

Fig. 4.10.3.5. Antegrade intramedullary nailing of the humerus with the T2 proximal humerus intramedullary nail

system Fig. 4.10.3.6.Patient in the ªbeach chair positionº

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entry point can be marked with a 3-mm Kirsch- ner wire, which can then be forwarded in the medullary canal under image intensifier control.

In this case the canal is opened with a cannulated 10-mm drill or, ideally, a special 10-mm reamer.

Reduction of the Fracture

and Intramedullary Reaming of the Medullary Canal Using the cannulated awl, it is now possible to ad- vance a guide wire up to the distal humerus with image intensifier control. For reamed intramedullary nailing, the 2.5-mm ball tip guide wire is used.

For unreamed intramedullary nailing, the 2.2-mm smooth tip guide wire is employed. In patients with multilevel fractures, in particular, special reduction tools can facilitate repositioning of the fracture fragments (Fig. 4.10.3.7). For reamed intramedullary nailing, the medullary canal is now reamed gently in increments of 0.5 mm with the guide wire.

Nail Selection and Insertion

First the appropriate nail length is selected. The intramedullary nail should be flushed with the cortex proximally and extend up to approximately 1 cm above the olecranon fossa distally. When se- lecting the correct nail length, the planned locking option (which depends on the type of fracture) should be taken into account (see below).

Several types of rulers are available for determin- ing nail length.

The nail diameter can be determined with an X-ray template; alternatively, the diameter of the last reamer used can be taken as a guide value.

The nail selected is attached to the target device and inserted into the humerus with the 2.2- mm smooth tip guide wire. Insertion should be primarily manual. Problems may occur at the out- set if the nail impinges on the medial cortex proximally and if it traverses the fracture zone.

Aggressive advancement of the nail should be avoided here to prevent additional fracturing.

The correct insertion depth of the nail, which also depends on the locking option selected, can be checked using the markings on the target device (Fig. 4.10.3.8). The groove markings should be at the level of the cortex of the humeral head here.

When inserting the nail further toward distal, fracture dehiscence due to the nail should be avoided.

Locking and Compression

Proximal locking is carried out via the target device (Fig. 4.10.3.9). There are three different locking options ± static, dynamic and apposition/

compression ± that can be selected to match the requirements for different kinds of fractures. In addition, the surgeon has the choice of a diagonal or a transverse screw posture (Fig. 4.10.3.10).

Static locking guarantees rotational and axial stability and is therefore indicated for instable fractures and comminuted fractures. The short tissue protection sleeve is inserted ± along with the short drill sleeve and short trocar ± into the static locking hole of the target device and posi-

Fig. 4.10.3.7.Special reduction tool

Fig. 4.10.3.8. Checking the insertion depth of the nail as a

function of the locking option Fig. 4.10.3.9.Diagonal static locking proximally via the target device

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tioned on the cortex of the proximal humerus via a stab incision. Drilling is carried out with a 3.5´

230-mm drill; screw length can be directly read off the scale on the drill. In addition, a screw gauge has been provided for the determination of correct screw length; this gauge is inserted over the short tissue protection sleeve. The 4-mm locking screw selected is then screwed in via the short tissue protection sleeve. When the transverse locking option is taken, care should be exercised not to perforate the opposite cortical substance in the interest of preventing an intra-articular screw position.

Consequently, in patients with poor bone sub- stances in the humeral head, the diagonal locking option should be chosen, since, with this option, the opposite cortical substance can be drilled without the danger of screw perforation into the joint. The second locking screw is placed in an analog manner. Distal locking is performed using a freehand technique with a radiolucent drilling device.

Dynamic locking does not make much sense in the upper extremity. However, this locking option constitutes the technical prerequisite for compression or apposition locking. In fractures with axial stability, interfragmentary compression can in- crease fracture stability and improve fracture healing. First, distal freehand locking is carried out using the radiolucent drilling device. Prior to locking, the correct insertion depth of the nail (Fig. 4.10.3.8) and the rotational alignment should be rechecked. As a result of the compression, the

nail is pulled out of the proximal fragment; for this reason it is necessary to insert the nail deep- er in the humerus, paying attention to the markings on the target device. Subsequently, the proximal slot is occupied with a 4.00-mm shaft screw in the dynamic hole of the target device. For the purpose of inserting the compression screw, the nail-holding screw must be removed from the target device. Subsequently, the compression screw can be screwed in with the special screwdriver.

There is a marking on the screwdriver shaft.

When this marking reaches the target device, the compression mechanism starts. An image intensifier should be used to control the compression procedure in the fracture zone. Compression can also be detected indirectly by the bending of the shaft screw. If the compression screw is screwed in completely, a connection displaying angular stability will be created between the nail and the locking screw.

After compression locking, it is possible to achieve a complex compression locking affording additional stability and relief of the shaft screw by occupying the proximal transverse locking hole.

Compression locking can also be carried out in the form of fracture apposition in patients with dehiscence of the fracture. Since the aim of apposition locking is to bring the fracture ends closer together (and not to compress the ends), this technique can also be used to treat fractures with axial instability. The principle is identical to that of compression locking. The only difference is that the procedure of screwing in the compression screw is terminated as soon as bone contact has been achieved.

End Cap Insertion

Nail insertion is completed by screwing in the end cap. The end caps come in several lengths;

they can thus be used to lengthen a nail that has been inserted too deeply. The option enables the surgeon to anchor the nail stably in the proximal cortex of the humeral head and facilitates material removal. Screwing in the end cap firmly creates a stable connection with angular stability between the intramedullary nail and the proximal locking screw that has been inserted transversally.

Follow-up Treatment

One of the main advantages of intramedullary nail osteosynthesis is the high stability achieved

Fig. 4.10.3.10.Proximal locking options (diagonal and transverse)

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by the implant. As a rule this ensures early functional follow-up treatment and a speedy return of the patient to his/her everyday life. In patients who have undergone antegrade intramedullary nailing, for example, the disadvantage of the surgical trauma (with potential damage to the rotator cuff) can be minimized by starting physiothera- peutic exercise treatment as early as possible.

Retrograde Intramedullary Nailing

During retrograde intramedullary humeral nailing, the nail is inserted from distal toward proximal. The patient is placed in the prone position.

For this reason, this method is of only limited applicability for patients with concomitant pulmonary and/or cardiac disease as well as for patients with multiple trauma including craniocer- ebral trauma and/or chest, abdominal or spinal column injuries.

An additional problem associated with this method is the relatively high rate of iatrogenic fractures in the vicinity of the nail entry point; in the literature this complication is reported in up to 8% of cases [1, 6]. In connection with proximal freehand locking, the dorsoventral locking option still poses the risk of injury to the axillary nerve [3].Several authors report a higher incidence of pseudarthrosis in connection with retrograde intramedullary nailing. Since no cause specific for a particular method has been identified so far, we have to conclude that this complication is due to technical problems.

Numerous studies have been carried out to as- sess postoperative shoulder and elbow function in relation to the individual techniques used for intramedullary nailing. The researchers performing these studies conclude unanimously that, provided the nail is inserted correctly, there is no sig- nificant detrimental effect on elbow function after either antegrade or retrograde procedures. A comparison of the studies exploring functional outcomes in the shoulder joint, in contrast, reveals no uniform conclusions. The only point of agree- ment among the various authors is the early functional limitation of shoulder joint function ob- served after antegrade intramedullary nailing.

After several months, however, there was no sig- nificant difference in shoulder function in patients treated with the different methods.

Retrograde intramedullary nailing of the humerus is the more complicated of the two methods and is, on the whole, associated with more complications.

Positioning

Surgery is performed with the patient in a prone position. The injured upper arm is supported on an arm board. The shoulder is abducted by 908;

the elbow joint is flexed by 908 (Figs. 4.10.3.11 and 4.10.3.12). Maximum elbow flexion is a prerequisite for inserting the nail without any diffi- culties.

In comparison with antegrade intramedullary nailing, patient positioning is distinctly more complicated here; in a number of patients with concomitant pathology or injuries, it is in fact im-

Fig. 4.10.3.11.Retrograde intramedullary nailing of the humerus

Fig. 4.10.3.12.Positioning of the patient for retrograde intramedullary nailing

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possible. It must be possible to visualize with the image intensifier the nail entry point on the distal humerus and the region of the humeral head where proximal freehand locking has to be carried out. This can be difficult, especially in the humeral head, since the nail should be advanced far toward proximal.

Access and Entry Point

The main incision starts at the olecranon tip and proceeds in a proximal direction. The triceps tendon is split, and the distal humerus and the proximal part of the olecranon fossa is exposed.

The nail entry point is located 1 cm proximal to the olecranon fossa. The insertion template for the distal humerus is placed on the humerus;

using a 3.5 mm drill, several holes are then drilled in the dorsal cortex (Fig. 4.10.3.13). The row of drill holes can now be expanded to form an oval window approximately 3 cm in length (Fig. 4.10.3.14). The preparation of this bone window is one of the most important steps during the operation. Even though the end of the nail ex-

hibits a distal curvature of 48 to facilitate insertion, the entry point must be wide enough that the insertion of the nail does not provoke any new fractures of the humerus.

Reduction of the Fracture and Intramedullary Reaming of the Intramedullary Canal

With the patient's arm supported on the arm board, fracture reduction can be carried out without any difficulty. The correct rotational alignment is established virtually independently by the vertically suspended lower arm.

Reduction and drilling are carried out in the same manner as during antegrade intramedullary nailing.

Here again the T2 nail can be inserted via a reamed method (which we personally prefer) or an unreamed method. A guide wire is used during both nail insertion procedures; during retrograde intramedullary nailing, this wire is advanced up to the center of the humeral head.

Nail Selection and Insertion

For surgeons planning a retrograde intramedullary nailing procedure, there are ± as for the antegrade procedure ± a number of tools available that facilitate the task of nail selection. The planned locking technique should be taken into consideration when deciding on nail length; this prevents impairment of elbow joint extension caused by impingement of an overly long nail.

With regard to nail diameter, the thickest nail that can be inserted without difficulty should be selected.

Locking and Compression

The locking options available for retrograde intramedullary nailing do not differ from those used for the antegrade technique.

Owing to the oblong form of the entry hole in the distal humerus, there may not be a sufficient bone bridge to the drilled hole for the distal locking. In this case washers can be used for bridg- ing.

Follow-up Treatment

Questions of functionality are also in the fore- ground in the follow-up treatment of patients

Fig. 4.10.3.13.Preparation of the nail entry point with drilling template and rigid reamer

Fig. 4.10.3.14.Preparation of the nail entry point with drilling template and rigid reamer

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after retrograde intramedullary nailing of the humerus. In view of the good results achieved with conservative brace therapy, load-stable osteosynthesis with good shoulder and elbow function is the prime goal of operative treatment.

Summary

The range of indications for operative treatment of humeral shaft fractures has expanded markedly in recent years. Whereas plate fixation is the procedure of choice for several special indications, e. g. pseudarthrosis, peri-implant fractures, and extremely distal shaft fractures, intramedullary nailing is becoming the standard surgical treatment for humeral shaft fractures for several reasons:

· The new intramedullary implants offering several locking options represent an ideal merger of the advantages of minimally invasive biological osteosynthesis with a high degree of stability in the treatment of fractures, even in osteo- porotic bone.

· Interfragmentary compression and apposition are additional options as part of an optimal fracture treatment program aimed at minimizing delayed bone healing and pseudarthrosis formation.

· The implants lay the foundation for functional follow-up treatment, rapid restoration of weight-bearing capacity in the injured extremity, and thus a speedy return of the patient to his/her job and everyday activities.

· The range of instruments permits a safe surgical technique and short operation times.

At our hospital, antegrade intramedullary nailing of the humerus is now a standard treatment for humeral shaft fractures for several reasons:

· The uncomplicated positioning of the patient in the ªbeach chair position,º which, in contrast to the prone position required for the retrograde approach, is also an option for patients with concomitant pulmonary disease, cardiac disease or multiple trauma.

· The proximal access to the humerus, which results in comparable functional results for

shoulder and elbow function while minimizing the risk of iatrogenic fracture.

· The fact that extremely proximal fractures and combination injuries involving fractures of the humeral head and shaft are ideally treated via an antegrade procedure making use of the long versions of the proximal intramedullary humeral nail possessing angular stability.

References

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