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Original Article

Antegrade Nailing of Humeral Head Fractures with Captured Interlocking Screws

Linhart, Wolfgang MD*†; Ueblacker, Peter MD*; Groterlinden, Lars MD; Kschowak, Philipp*; Briem, Daniel MD*; Janssen, Arne MD*; Hassunizadeh, Behrus MD*; Schinke, Marte MD*; Windolf, Joachim MD*†; Rueger, Johannes Maria MD*

Author Information
Journal of Orthopaedic Trauma: March 2008 - Volume 22 - Issue - p S46-S55
doi: 10.1097/BOT.0b013e318059b5a1
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Abstract

INTRODUCTION

Proximal humeral fractures represent 4% to 5% of all fractures in adults with an increasing expectation of greater numbers.1-3 Approximately 80% to 85% of these fractures yield a good functional result after nonoperative treatment.4 Although elderly individuals often have much lower functional requirements, and the results of nonoperative treatment may therefore be satisfactory,5-7 nonoperative treatment is not recommended for unstable fractures of the proximal humerus. Various operative methods are reported in the literature for unstable and 3-4 part comminuted fractures.8-19 In 4-part fractures, the relative merits of reduction and fixation versus hemiarthroplasty are controversial.20 Other factors regarding treatment options include: osteoporosis that can often pose problems regarding secure fixation of the implant of choice, and the proximity of the brachial plexus and the vascular anatomy of the proximal humerus, which can be impaired secondary to the trauma (rarely) and surgical intervention.21-22

Common therapeutic methods include percutaneous fixation with the use of Kirschner wires and/or tension band,8,14 fixation with a cloverleaf plate9 or a locking plate.23-24 Minimally invasive procedures, such as intramedullary fixation with elastic nails or pins,18-19 Seidel nails,25 and various other intramedullary nails with options such as interlocking screws to confer additional stability were developed to preserve the blood supply of the humeral head.

Until recently, no study reported satisfactory results for intramedullary devices in the management of 3-part and 4-part fractures, due to the inability of these devices to control displaced tuberosity(s).20 Only a few studies in the past few years describe promising results with newer devices, the Polarus nail14,26-27 and the Targon PH nail.28-31 Both of these devices are able to control displaced tuberosity(s) with the addition of fixed-angle locking screws.

The goal of the present study was to assess the functional outcome in a series of patients in whom a proximal humeral fracture was treated with the new antegrade intramedullary Targon PH nail with proximal interlocking screws; a device that provides angular and sliding stability due to threaded holes in the proximal part of the nail.

PATIENTS AND METHODS

Ninety-seven patients with a proximal humeral fracture were treated with the proximal humeral nail (Targon PH; Aesculap, Tuttlingen, Germany) between April 2000 and March 2004. Targon PH-nails with the length of 150 mm were used. All patients were evaluated after 6 months, 51 patients (52.6%) after 12 months, and 31 patients (32%) after 24 months. Exclusion criteria were pathological and head-split fractures as well as proximal humeral fractures in multiply injured patients.

This study focuses mainly on the patients with a follow-up of 1 year. There were 39 (76.5%) women and 12 (23.5%) men. The mean age was 68.4 ± 15.0 years (range, 33 to 90 years). Thirty-five patients (68.6%) were older than 60 years, and 11 patients (21.6%) were older than 80 years of age.

The right shoulder was affected in 21 cases (41.2%), and the left shoulder in 30 cases (58.8%). The average delay from time of injury to operation was 1.1 ± 1.4 days (range, 0 to 7 days). The average time of operation was 82.8 ± 39.3 minutes. All patients were treated with a standard single dose antibiotic and antithrombotic prophylaxis regimen for the first few days.

The study was not approved by our IRB, but every patient was asked for her/his explicit agreement to take part in the study.

Fracture Classification

Although studies reported about limited interobserver and intraobserver reliability,32-33 all fractures were classified with use of radiographs done on the day of trauma using the AO/Association for the Study of Internal Fixation system (ASIF)34 and the Neer classifications.35 We observed the following distribution of fractures according to these classifications in our 97 patients.

According to the Neer system, we treated 26 (26.8%) 2-part, 64 (66%) 3-part, and 7 (7.2%) 4-part fractures. We also treated 1 patient with a 1.1 fracture and 1 patient with a posteriorly dislocated VI.3 fracture.

According to the AO/ASIF classification system, there were 25 (25.8%) A-types, 46 (47.4%) B-types, and 26 (26.8%) C-types. See Tables 1 and 2 for the detailed distribution of fracture types.

Table 1
Table 1:
Indications for the Implantation of the Targon PH Nail of 97 Patients According to the AO/ASIF-Classification
Table 2
Table 2:
Indications for the Implantation of the Targon PH nail of 97 Patients According to the Neer-Classification

Indications

There is a wide range of indications, including combined meta- and diaphyseal fractures or distal fractures type A, B, and C according to the AO/ASIF classification.

Neer type-III, IV.3, and V.3 fractures were considered ideal indications for implantation of the Targon PH nail. Other indications were Neer type IV.4, V.4, and VI.3 fractures with intact head fragments. Although not a standard indication for surgery, we treated 1 patient with a I.1 fracture; this patient was a young and active and demanded early rehabilitation.

The size of the humeral head fragment must be of sufficient size to determine the entry point for the nail. An intact bony ring around the nail should be conserved to ensure stability. In 4-part fractures, the contact of the fragments and stability seems to be more important than an anatomical reconstruction.

Fractures involving only the greater or lesser tuberosity and head-splitting fractures were not thought to be indications for treatment with this nail. Even though nondisplaced fractures (Neer I.1) are not ideal indications, treatment with the Targon PH nail has the advantage of immediate stability of the fracture, which allows almost pain-free early mobilization of the shoulder especially in younger, active patients.

Nail

The diameter of the nail (10 mm proximal and 8 mm distal) was designed as small as possible to avoid tissue trauma. The design incorporates 4 fixed-angle locking screws in its proximal part, each placed at a different level of the humeral head considering the anatomic position of the main fragments (Figure 1). The entry points and central axes of 2 fixation screws are positioned on a zero-line at the lateral portion of the greater tuberosity. The entry points and central axes of the 2 additional screws are positioned at 55 degrees and 70 degrees of deviation from the zero-line (at the dorsolateral portion of the greater tuberosity and the main portion of the lesser tuberosity), resulting in a 3-dimensional construct. The interlocking screws are responsible for angular and sliding stability. The screws penetrate the tissue only at certain points; therefore, possible damage to the blood supply of the humeral head is limited to a minimum. In 3-part and 4-part fractures according to Neer, the configuration of these 4 screws allows for fixation not only of the proximal fragment but also of the greater and lesser tuberosity. Rotational stability is achieved by using 2 distal interlocking screws. Noncompressive fixation seems to be particularly advantageous in osteoporotic bone, where compression of the fragments could lead to further damage and consecutive increasing instability of the fragments.30-31

FIGURE 1
FIGURE 1:
Design of the Targon PH nail. Depending on the fracture type, 2 to 4 interlocking screws can be placed to stabilize the humeral head fragments. The zero-line for the entry of the 2 lateral proximal fixation screws is at the lateral portion of the greater tuberosity next to the bicipital groove. The axes of the additional screws are positioned at 55° and 70°, thus a right and a left version of the implant are required. At the far right figure, the anatomical position of the axillary nerve as indicated by the arrows should be noticed when placing the distal locking screws.

The nail is available in 150-mm, 220-mm, 250-mm, and 280-mm lengths. The asymmetric anatomic positioning of the dorsolateral greater and lesser tuberosity fragment with regard to the reference line makes a right and left version necessary. This study focuses only on cases in which a nail with a length of 150 mm was used for the treatment of isolated fractures of the proximal humerus.

Surgical Technique and Postoperative Treatment

The patient is placed in a beach-chair position on a shoulder table. A closed reduction is performed if possible under flouroscopic control in 2 planes (true ap and transscapular view). Surgical access is achieved through a deltoid-split at the front of the acromial margin. After opening the subacromial bursa, a longitudinal incision in the rotator cuff in the direction of its fibers exposes the humeral head (Figure 2A). Holding sutures are placed in the edges of the supraspinatus tendon. If closed reduction is not successful, a mini-open reduction is performed with the use of a Kirschner wire (2.5 mm) as a joy-stick for the humeral head and a small hook for the reduction of the tuberosities (Figure 2B). In displaced fractures, Kirschner wires can be temporarily placed to hold reduced fragments. After reduction of the head fragment, the guide pin is inserted at the most cranial point of the humeral head. An intact bony ring must be present all around the entry point. A fluoroscopic check in 2 planes must confirm the entry point, which is about 8 mm medial to the cartilage-bone transitional zone at the sulcus between the head and the greater tuberosity (Figure 2B). The entry hole of the nail is opened with a hollow reamer (10.5 mm in diameter) used over the guide pin. The nail is then inserted manually. If the correct entry point has been selected, an anatomical alignment of the head and the shaft fragment should be accomplished during insertion of the nail (Figure 2C). The optimum depth of the nail insertion should be 3 to 4 mm below the cartilage to prevent damage to the rotator cuff by an overriding proximal nail tip and to avoid subacromial impingement. This depth can be achieved with use of a specific scale. Using the targeting device allows insertion of the fixation screws. Depending on the number of fragments, type of fracture and quality of bone, 2 to 4 4.5-mm fixed-angle screws are used (Figure 2, D to F). In comminuted areas, spike-washers can be used with the screws. Two distal fixation screws can then be placed (Figure 2, G to H). After removal of the targeting device, the rotator cuff and the deltoid are sutured side-to-side, and a wound drain is inserted before skin suture.

FIGURE 2
FIGURE 2:
(A) Approach to the fracture through a deltoid-split at the front of the acromial margin. (B) Reduction of the humeral head with use of a Kirschner wire (2.5 mm) as a joy-stick. Insertion of the guide pin and fluoroscopic check in 2 planes. (C) Reduction of the fracture with use of the targeting device. (D-F) Optimum depth of the nail is 3 to 4 mm below the cartilage surface. Proximal and distal fixation screws are inserted with use of the side-specific guide. Postoperative (G) anteroposterior and (H) transscapular radiographs.

A shoulder immobilizer sling (eg, Gilchrist) is applied with the upper limb in internal rotation, neutral flexion, and abduction; it is used for 5 to 7 days. Passive range-of-motion exercises are done immediately, and active-assisted range-of-motion exercises are started 4 days after the operation with pain-dependent free elevation and abduction. All patients underwent a formal rehabilitation protocol with recommendations to avoid forced rotation and axial forces for 6 weeks.

Seven surgeons were involved in the care of our patients. All of them were consultants with a minimum of 10 years of surgical experience.

Outcome Measures

Radiographic evaluation was performed by the radiographic staff from the Department of Radiology and Radiological Intervention, which is independent of the Department of Trauma, Hand and Reconstructive Surgery. Clinical evaluation was done by an independent research fellow and 2 medical students who were not involved in the care of the patients but were not blinded. Clinical follow-up examinations were performed 6, 12, and 24 months after operation. The functional outcome was assessed with the standard Constant-Murley36 and Neer scores,37 modified by Kristiansen et al,38 without radiological follow up. The examination of the patients was performed, and all criteria were applied as described in the original publications. The functional outcome was measured using the score of the affected side as a percentage of the score on the unaffected side (relative score). Additionally, functional photos were taken, and all potential or manifest complications were recorded.

Statistical Analyses

All data are given as mean value ± standard deviation. Differences between the groups were evaluated by the standard t-test. If the sample data were not normally distributed, the Mann-Whitney rank sum test was used instead. All tests were calculated with a desired power of β = 0.8 and a significance level of α = 0.05. Statistical analyses was performed with SigmaStat (version 2.03) by SPSS.

RESULTS

Of 97 patients, 51 (52.5%) completed a 12-month follow-up. Three patients died from unrelated causes, 21 could not be contacted by telephone or mail, 15 persons refused to take part in the study, and 7 patients could not be evaluated due to medical reasons, such as severe dementia or severe illness.

Functional Outcome

The total Neer as well as the Constant-Murley scores demonstrated a gradual improvement from 6 months to 12 months postoperatively. The mean absolute Constant-Murley score on the injured side increased from 59.5 ± 18.2 points at 6 months to 71.2 ± 16.1 points at 12 months and slightly decreased to 68.2 ± 19.7 points at the last follow-up after 2 years (Table 3). The mean Constant-Murley score on the injured side, expressed as a percentage of the scores on the noninjured side (relative score) increased from 71.7 ± 18.3% at 6 months to 82.1 ± 14.1% at 12 months and to 80.2 ± 17.5% at 24 months postoperatively. These results show a highly significant improvement from 6 months to 12 months postoperatively (P < 0.001) but no significant further improvement or decrease at later follow-ups.

Table 3
Table 3:
Functional Outcome Over Time According to the (A) Absolute Constant-Murley Score and the (B) Relative Constant-Murley Score. The Mean Relative Constant-Murley Score on the Injured Side Increased Significantly from 71.7 ± 18.3% at 6 Months to 82.1 ± 14.1% at 12 Months (*P < 0.001)

The mean relative Neer-Score (excluding the anatomic score) of the injured shoulder demonstrated an improvement from 78.1 ± 22.8% at 6 months to 84.7 ± 14.1% at 12 months and 83.5 ± 16.3% at 24 months. These results also show a highly significant improvement from 6 months to 12 months postoperatively (P < 0.001), but no significant further improvement or decrease at later follow-up times.

Subdivision of the total Neer and Constant scores into their parameters revealed that each parameter demonstrated a similar increase over the observation period. Subdivision into arbitrary age groups (≤60, >60, and ≥80 years) revealed a tendency of better results for patients younger than 60 years compared with patients older than 80 years (Table 4). Patients younger than 60 years of age reached a mean relative Constant score of 87.2%, patients older than 60 years 79.4%, and patients older than 80 years 75.9% (Table 4) (Figures 3 and 4).

Table 4
Table 4:
Age-related Functional Outcome According to the Relative Constant-Murley Score of 51 Patients 12 Months After Implantation.
FIGURE 3
FIGURE 3:
An 80-year-old female patient with a Neer-type V.4 fracture of the left proximal humerus. (A-C) Preoperative anteroposterior and transscapular radiographs and CT scan. (D-E) Postoperative anteroposterior and transscapular radiographs at 2 days after surgery. The relative Constant-Murley Score increased from 67% at 6 months to 83% at 12 months after operation.
FIGURE 4
FIGURE 4:
A 40-year-old female patient with a Neer VI.3 fracture of the right proximal humerus. (A-E) Preoperative anteroposterior and transscapular radiographs and CT scan demonstrating the fragments and the posterior dislocation of the humeral head. (F-G) Anteroposterior and transscapular radiographs taken after 2 years showing the complete healing of the fracture. The relative Constant-Murley Score at 24 months after the operation was 98%.

No significant differences were found in patients with 2-part, 3-part, and 4-part fractures regarding functional outcome (Table 5).

Table 5
Table 5:
Relative Constant-Murley Score of 51 Patients 12 Months After Implantation Related to the Number of Fracture Fragments.

Of interest, in the course of the removal of a dislocated proximal fixation screw, we performed a glenohumeral arthroscopy of a 55-year-old male patient 6 months after implantation of a Targon PH nail. Due to a thorough side-to-side closure of the supraspinatus tendon in the first operation, neither a rotator cuff tear nor a chondral damage of the humeral head was found. The former entry point of the nail was completely filled with fibrochondral tissue flush with the adjacent cartilage (Figure 5). Since this is a single observation, we cannot state if comparable results can be found in other patients treated with the Targon PH nail.

FIGURE 5
FIGURE 5:
Glenohumeral arthroscopic assessment 6 months after implantation of a Targon PH nail. The insertion sites on the supraspinatus tendon (*) and the humeral head (↑) are still visible. Due to a thorough closure of the tendon, there are no signs of a lesion. The entry hole of the nail on the humeral head is filled with fibrocartilage and flush with the adjacent cartilage. Neither inflammatory nor osteoarthritic signs were observed.

Complications

Ten complications (19.6%) were recorded in 51 patients (Table 6). The most frequent complication was a loosening or dislocation of the proximal fixation screws in 5 cases (related to III.2 and IV.3 fractures). One or more screws had to be removed operatively in 4 cases. Symptoms associated with the screws resolved after their removal. In the 1 other case, a secondary dislocation of the humeral head fragment was found at time of surgery. In this case, an excisional arthroplasty had to be performed because of the patient's age and poor general condition.

Table 6
Table 6:
Complications in 51 Patients Recorded at Follow up at 12 Months Postoperatively.

Complete osteonecrosis of the humeral head was found in 1 patient with a IV.3 fracture, this was treated by implant removal and secondary hemiarthroplasty. Partial osteonecrosis of the humeral head developed in 2 patients with IV.4 fractures and 1 patient with a IV.3 fracture. Secondary hemiarthroplasty was used to treat 2 of these patients. In the third patient with partial necrosis of the humeral head, no specific treatment was necessary because of the lack of clinical symptoms.

No other complications, such as soft tissue infections and painful hardware, were seen in our patients.

DISCUSSION

The optimal therapy of proximal humeral fractures is still subject to controversy, and accepted guidelines are lacking.39-40 Minimally invasive implants, such as flexible intramedullary implants did not show good results in the management of 3-part and 4-part fractures in adults due to their inability to control the displaced tuberosity(s).20

Newer devices, such as the Polarus nail and the Targon PH nail with precise targeting devices, were recently developed as a therapeutic alternative for metaphyseal fractures. These implants are angular stable, and they rely on the increased stability produced in the osteoporotic bone-implant construct to allow osseous healing with a reduced risk of secondary loss of reduction.14,26-27,30-31

The Targon PH nail is one of the first implants in which the concept of a straight, short interlocking nail has been realized. In most 3-part and 4-part fractures, 1 of the fracture lines is found between the greater tuberosity and the head fragment. Since an intact bony ring has to be preserved, the insertion point of the nail is crucial. The straight Targon PH nail is inserted medially to the fracture line in classical 3-part and 4-part fractures. A disadvantage of this insertion point is the fact that it is located within the articular cartilage. When no intact bony ring is available (such as head-splitting fractures), a locking plate can be useful instead of the nail.

In 3 recent studies, the Polarus nail was found to be a satisfactory device.14,26-27 All of them recommend the use of the Polarus nail for 2-part, 3-part, and 4-part fractures. Rajasekhar et al14 evaluated 30 proximal humeral fractures. Satisfactory to excellent results were realized in 80% of the patients. Only 1 fracture (3%) developed a nonunion. Adedapo et al26 reported on 23 fractures. A large percentage of patients had complete pain relief. Three patients (13%) developed painful proximal screw loosening and required screw removal. One patient (4%) developed avascular necrosis with humeral head collapse. Agel et al27 undertook a chart review of 20 patients. Eleven fractures (55%) healed without complications. Three (15%) had proximal fixation screw loosening, and two patients (10%) underwent revision surgery for proximal fixation failure. Fractures that had lateral starting points with associated metaphyseal comminution were likely to displace into less than 120° of valgus neck/shaft angle. The authors concluded the Polarus nail is not an effective implant in unstable or comminuted lateral metaphyseal fracture, if the starting point extends into the greater tuberosity, because fixation failure or fracture displacement may result.

Mittlmeier et al treated 221 patients with a standard or long Targon PH nail, and 64 patients were followed for 1 year.30 The mean relative Constant-Murley score after 12 months was 85.7 ± 15.9%. Patients with 4-part fractures had a significantly poorer outcome. There were 59 complications in 115 patients (51%); 48 required reoperation, but the majority of the complications were minor, easily treated implant-related problems, such as backing out of fixation screws. The authors found the nail to be a satisfactory device, even in osteoporotic bone, and concluded that an even better functional outcome may be expected in the patients with further observation. Mathews and Lobenhoffer evaluated 41 patients with a mean age of 81 years; all of them were older than 60 years of age.29 After a follow-up of 13 months, the relative Constant-Murley score reached 90 ± 7%. Complications that required a second operation occurred in 3 patients (7%). Stedtfeldt et al treated 45 patients, 17 of them were followed for 12 months.31 At this time point, they had reached a Constant-Murley score of 85.7 points. Complications were recorded in 16% of the patients.

The present study included 51 patients with a mean age of 68 years and a mean relative Constant-Murley score of 82.1 ± 14.1% after 1 year is in accordance with the data published by Mittlmeier et al.30 In contrast to the suggestion of Mittlmeier, our results on patients with a follow-up of 24 months indicate that there is no further improvement of the functional outcome after 1 year. To demonstrate that not only younger patients reach good results after implantation of an intramedullary nail, we evaluated our data in different age groups. As expected, patients younger than 60 years of age demonstrated a tendency for better results compared with patients older than 80 years of age. However, there was no statistically significant age-related difference concerning the functional outcome. Even the oldest age group achieved good results with a mean relative Constant-Murley score of 78% after 1 year. Unexpectedly, there were no significant differences among patients with 2-part, 3-part, and 4-part fractures concerning the relative Constant-Murley score. Thus, good and excellent results can be achieved even in elderly patients with complex fractures.

We observed 10 complications in 51 patients, 5 minor and 5 major complications. Some of the implant-specific problems, such as the backing out of proximal fixation screws could be reduced by technical modifications. The company has already developed a new locking mechanism of the proximal screws (PEEK-inlay) to avoid this problem.

In 1 patient, we documented a fixation failure and a secondary dislocation. The authors did not find a discernible reason for this complication in this specific case.

As the peak values of histomorphometric parameters and bone strength are located in the cranial section of the humeral head and decrease caudally,41 another crucial point is not to insert the humeral nail too deeply. We recommend insertion of the Targon PH 3 to 4 mm under the articular cartilage surface.

In contrast to Mittlmeier et al,30 it is our protocol to do a preoperative computerized tomographic scan to obtain a precise classification of the more complex fractures. In our opinion, this concept has the advantage of a better preoperative understanding of the fracture pattern. Primary hemiarthroplasty treatment for these fractures in older patients gives good pain relief, but the functional Constant scores average around 50 points.42-44 The increased functional Constant scores in our patient study has influenced our thinking for the use of intramedullary fixation using the Targon PH nail rather than primary hemiarthroplasty for complex fractures. However, if the humeral head is devoid of soft tissue attachments or is technically unreconstructable, shoulder hemiarthroplasty must be performed.

The present study represents a series of a singular implant, the Targon PH, which was evaluated since its market launch. An obvious limitation of the study is the high rate of patients who could not be followed for 1 year or more.

In conclusion, intramedullary fixation using the Targon PH humeral nail was associated with satisfactory functional results in our series. The operative technique is demanding, but it results in a stable fixation and allows for an early start of active physiotherapy even in elderly patients. We consider this to be the main reason for the satisfactory functional outcome in the majority of the patients.

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Keywords:

proximal humeral fracture; straight nail; osteoporosis; antegrade nailing; Targon PH

© 2008 Lippincott Williams & Wilkins, Inc.