Internal fixation of proximal humeral fractures with a Polarus humeral nail
© Springer-Verlag 2008
Received: 23 November 2007
Accepted: 7 June 2008
Published: 16 July 2008
Proximal humeral fractures occur frequently. Displaced or unstable fractures require open reduction and internal fixation. Our objective was to investigate the clinical and radiographic results of the internal fixation using Polarus humeral nails for fractures of the proximal humerus.
Materials and methods
From January 2001 to April 2006, 54 shoulders of 54 patients (44 females, 10 males) underwent the intramedullary fixation using Polarus humeral nail. Mean age of the patients was 66-year-old (39–89) at the time of the surgery. Fracture-type by Neer classification was 2-part (29 shoulders), 3-part (22 shoulders) and 4-part (3 shoulders). The clinical and radiological outcomes were evaluated.
All the shoulders after osteosynthesis obtained bone-union. There was no osteonecrosis of the humeral head. Functional outcome measured by JOA score averaged 81 points. Totally 43 patients (79%) had satisfactory to excellent results. Varus deformity was seen in 4 shoulders (8%) and the deformity of the greater tuberosity in 4 (8%).
The Polarus intramedullary humeral nail is effective for the treatment of proximal humeral fractures.
Proximal humeral fractures occur frequently. Most proximal humeral fractures are minimally displaced or non-displaced and are treated conservatively with good results. However, unstable or displaced fractures may lead to non-union, malunion or limited function . Therefore, these displaced or unstable fractures require operative reduction and stabilization for favorable outcome. Various devices have been proposed for fixation, including plates and screws, staples, wire, multiple pins, intramedullary nails, and combination of these items. Intramedullary fixation has been thought as less invasive because it, compared with plate fixation, requires less extensive soft tissue dissection [2, 3].
The Polarus intramedullary nail (Acumed LLC, Hillsboro, OR, USA) is a stabilization device specialized for proximal humeral fixation. It provides screw stabilization of the humeral head and the tuberosities. Published reports about using Polarus intramedullary nails for proximal humeral fractures are satisfactory [2–8], but unsatisfied results with high complication rate of up to 32% has also been reported .
The purpose of this report was to evaluate the clinical and radiographic results of the Polarus nail retrospectively. Our hypothesis was that Polarus intramedullary nail could be effectively used to treat displaced proximal humeral fractures.
Materials and methods
Number of patients
Under general anesthesia, the patient was placed in beach-chair position on a radiolucent operating table. A longitudinal skin incision was made along the greater tuberosity of the humerus. The deltoid muscle was bluntly split to expose the rotator cuff. In cases of 2-part (surgical neck) fracture, a Kirschner pin was inserted through the rotator cuff, and its position was confirmed by C-arm. A 10 mm longitudinal incision was made on the supraspinatus tendon right medial to the greater tuberosity and the entry portal of the nail was created with a drill and enlarged with a hand reamer. While maintaining fracture reduction by manual manipulation, a 2.0-mm guide wire was passed across the fracture and then the nail was inserted correctly. Finally, the nail was locked proximally and distally. In cases of 3- or 4-part fracture, the rotated or displaced articular fragment was reduced first and lined up with the shaft fragment. The entry portal of the nail was created on the articular fragment carefully, not to crack the articular fragment. Next, the displaced greater or lesser tuberosity fragment was identified and reduced. One suture inserted on the supraspinatus tendon pulled out the greater tuberosity fragment. The lesser tuberosity fragment was also manipulated by a suture inserted on the infraspinatus tendon. A guide wire was passed across the head-shaft fracture and then the nail was inserted. The fragment of greater or lesser tuberosity was reduced and then fixed with the locking screws or nonabsorbable sutures. Finally, the supraspinatus tendon and deltoid muscle were meticulously closed.
Postoperatively, the patient’s arm was supported in a neck sling. Active exercise of the elbow and wrist joint was encouraged immediately. Pendulum motion of the shoulder joint was started in 2 days and followed by passive elevation and rotation of the shoulder joints in the following week. Active motion was started at about 4 weeks. The patients are seen at 2, 4 weeks and at 3-month intervals.
Evaluation of the Polarus nail focused on the clinical and radiological outcomes. During the postoperative course, such complications as neurologic injury, avascular necrosis, infection and implant failure were recorded. Also, functional outcomes at 12 months was graded according to the Japanese Orthopaedic Association Shoulder score (JOA score), which has a maximum 95 points: 30 for pain, 20 for function, 30 for range of motion (ROM), and 15 for stability . The results were excellent for a score of 85–95 points; satisfactory, 75–84; unsatisfactory, 65–74; and poor, <65.
Functional outcome as measured by JOA score
Range of motion
Radiological outcomes as residual deformities
No. of patients
Deformity of the greater tuberosity
Proximal humeral fractures occur frequently. Displaced or unstable fractures require open reduction and internal fixation. Various treatment options are available but no single technique has been demonstrated to be superior or without complications [15–17]. The Polarus intramedullary nail (Acumed LLC, Hillsboro, OR, USA) is an intramedullary device for proximal humeral fixation. This study evaluated the clinical and radiographic results of the Polarus nail retrospectively.
The average operation time and the blood loss was comparable to other reports using the similar device . Absence of avascular necrosis of the humeral head was notable as it is one of the major complications after displaced fractures of the proximal humerus [1, 17, 18]. Besides the severity of the fracture, extensive soft tissue dissection has been cautioned as a major contributing factor . Sturzenegger et al.  reported a 34% incidence of avascular necrosis in a series of 17 patients treated with a T plate. The extensive exposure of the fragment for plate fixation was thought to compromise blood supply to the fracture-fragments in his series . We believe that intramedullary fixation jeopardizes less blood supply to the fracture-fragments because it requires less extensive soft tissue dissection.
The frequency of the loosening of the proximal cancellous screws (7%) was comparable to other reports, ranging from 4 to 20% [3, 5, 7, 9]. As Polarus nail didn’t have locking mechanism, the nail might have failed to hold the proximal cancellous screw. To prevent the loosening of the proximal screws, Inoue et al recommended that the second and third proximal cancellous screws should be ensured by penetrating themselves into the far cortex . These surgical method would reduce the screw loosening.
In this study, satisfactory functional recovery was obtained in 79%, a rate comparable with that reported in the literature, ranging from 75 to 80% [7, 9, 12]. Among the patients with unsatisfactory results, shoulder function was impaired by pain and loss of ROM. Degenerative shoulder problems before trauma have been reported to exert negative influence on functional prognosis . Wilmanns and Bonnaire  indicated the possible influence of a coexistent rotator cuff tear on functional recovery after proximal humeral fractures. The presence of painful hardware has also been reported as major risk factors causing stiff shoulder . In case where the stiff shoulder persists, performing an open release of adhesions with removal of painful hardware is recommended .
Although the rate of residual deformity (16%) was less desired, satisfactory bone union was obtained in all cases (100%). The present study supported the claim that as long as bone union is obtained, some residual deformities still lead to less-painful and functional activities . As many reports suggest, however, varus deformity of the humeral head might interfere with shoulder elevation  and the displaced greater tuberosity might cause subacromial impingement . Therefore the displacement should be corrected during the surgery, if possible.
The present study had limitations. Most of the study group comprised of selective patients with relatively preserved bone stock. Therefore the method used in the present study may not be applicable to patients with non-union, fracture-dislocation or severe osteoporosis. Also, longer follow-up of the patients may be necessary because osteoporosis, osteonecrosis or secondary osteoarthritis might develop or worsen at a later time.
Conflict of interest statement
The authors have no financial relationship with any organization that sponsored the research. The authors have full control of all primary data. The authors agree to allow the journal to review their data if requested.
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