Use of a Fibular Strut Allograft in an Osteoporotic Distal Humerus Fracture

Abstract

In 2004, nearly 120 000 fragility fractures of the humerus were reported. As the US population ages, this number is expected to increase. Fractures of the distal humerus can be treated in a closed or open fashion. Open treatment includes open reduction and internal fixation or total elbow arthroplasty. Open reduction and internal fixation typically involves dual plating for increased stability and early mobility. We present a case in which dual plating failed due to lack of screw purchase in osteoporotic bone. This patient’s fracture was then revised with the use of a fibular strut allograft for improved stability and screw purchase. This method of fixation has not previously been described in the distal humerus and may prove useful in open fixation of osteoporotic distal humerus fractures.

Introduction

The fastest growing population in the United States is made up of people 60 years and older. In light of this, osteoporosis is becoming more common.¹ This increase in osteoporosis has led to increasing numbers of patients presenting with low-energy fractures. In 2004, it was estimated that 10 million Americans older than 50 years had osteoporosis and that 7.9% of 1.5 million fragility fractures involved the humerus.²With nearly 120 000 osteoporotic humerus fractures occurring annually, it is important to understand the methods of treatment and indications for such treatments of these fractures. Popovic and King outlined indications for and outcomes of closed treatment, open reduction and internal fixation, and arthroplasty for distal humerus fractures.² They concluded that if open reduction and internal fixation is attempted for these fractures, dual plating is the gold standard. Dual plating provides greater fracture support and stability, which allows early range of motion.³ Despite the biomechanical benefits of dual plating, there is still concern that screw purchase in osteoporotic bone may be questionable. We present a case of a patient who was treated with dual plating for a comminuted distal humerus fracture. This construct then failed and her fracture was revised with a fibular strut allograft to aid in both stability and screw purchase. To our knowledge, the use of a fibular strut allograft for a distal humerus fracture in a patient with osteoporosis has not been previously described.

Case Presentation

The patient is an 84-year-old female with Alzheimer dementia. The patient presented to a level 1 trauma hospital following a fall that resulted in a closed comminuted right supracondylar humerus fracture—AO type 13 A3 (Figure 1). She underwent open reduction and internal fixation with a locking 3.5 mm posterolateral distal periarticular humerus plate and lateral 2.4 mm locking plate (Figure 2). She was noted to have poor bone quality and very thin cortical bone at the time of surgery. In a bulky soft dressing, she was discharged to a transitional care unit in stable condition. Gentle range of motion of the elbow was initiated 1 week postoperatively. She returned 10 days later with increased pain and swelling. Radiographs obtained at that time revealed that both the 3.5 mm and 2.4mm locking plates had failed by screw pull out (Figure 3).

Figure 1.

Presenting radiographs of an 84-year-old female with a comminuted supracondylar humerus fracture post fall.

Figure 2.

Intraoperative radiographs showing placement of 3.5 mm posterolateral distal periarticular locking plate with 2.4 mm locking plate and lag screw fixation.

Figure 3.

Fixation failure with screw pullout and loss of purchase of both the 3.5-mm and the 2.4-mm locking plates.

Following medical clearance, the patient returned to the operating room. Using the previous posterior incision, the distal humerus was exposed and the failed implants were removed. The fracture site did not appear to be infected, but tissue was taken and sent for cultures. A fibular allograft was then fashioned and positioned in the intramedullary canal via the fracture site. With some difficulty, the fracture was reduced over the fibular strut allograft. The allograft was provisionally held in position using a 2.0 mini fragment plate posteriorly with purchase in both native and allograft bones. A 9-hole 3.5 mm posterolateral distal humeral periarticular locking plate with a lateral flange was then contoured and placed with fixation through the patient’s native bone and the fibular strut graft. This was followed by placement of a 14-hole 3.5 mm medial distal humeral periarticular locking plate with screw fixation that traversed both the patient’s native bone and the fibular strut allograft when possible. Image intensifier confirmed excellent length, alignment, and rotation of the distal humerus. The wound was irrigated, a drain was placed, and the wound was closed. A posterior splint and shoulder sling were placed. The patient returned to the floor in stable condition.

Occupational therapy was initiated for wrist and hand range of motion exercises. She rested with the arm elevated to reduce swelling. Her drain was pulled on postoperative day 2. Intraoperative cultures grew rare coagulase-negative Staphylococcus species in the aerobic cultures. There was no growth in the anaerobic cultures. The infectious disease service was consulted and agreed that the cultures did not likely represent osteomyelitis. The patient was discharged to a transitional care unit on postoperative day 3. On discharge, she was stable and was sent to her nursing care facility with a 14-day course of amoxicillin with clavulanate.

Once the patient’s wound healed, the soft dressings were discontinued, and she was instructed to range her arm without restriction. Three months postoperatively, the patient had functional use of her arm without pain. Six months postoperatively, healing was complete radiographically.

Discussion

The use of a fibular strut allograft has been well recognized as beneficial in other situations that require additional bony matrix. Uses include treating nonunions in the proximal and diaphysis regions of the humerus as well as in the subtrochanteric region of the femur; following curettage for bone tumors; for femoral neck nonunions; and for periprosthetic fractures at the shoulder, hip, and knee.^4–17 Fibular strut allografts are often used when additional structure is needed and when ingrowth over time is desired. However, its use in a patient with osteoporosis with a distal humerus fracture has not been previously described to our knowledge.

Lateral dual plating as described by Prasarn et al was utilized in the initial surgery.³ In fact, our construct was highly similar to the construct presented in the technique article by Prasarn et al (Figure 4).³ Although they demonstrated excellent healing, our construct failed. Without adequate bone stock, dual plating may not be sufficient to allow early mobilization. Although medial and lateral plating at the time of the initial surgery was not performed, this may have been a more stable construct than the dual lateral plating we employed. It is impossible to know whether medial and lateral plating if used, would have failed. However, in light of the patient's considerable fracture comminution and poor bone quality, it is certainly conceivable that even this medial and lateral plating construct would have failed without allograft placement.

Figure 4.

Construct from Prasarn et al³ on the left; our intraoperative construct on the right.

Conclusion

This case demonstrates several important points when treating distal humerus fractures in patients with osteoporosis. In the presence of poor bone quality, if there is any concern with regard to adequate bony purchase, we recommend considering the use of additional bony matrix. As can be seen in Figure 3, when we treated this fracture without supplementing the bony matrix, the patient did not have adequate bony purchase to maintain fixation. However, once the fibular strut allograft was placed, bony purchase improved dramatically. Screws threaded through both medial and lateral locked distal humerus plates and strut allograft achieved adequate purchase to maintain the fracture in anatomic alignment while allowing incorporation of the strut allograft during healing (Figures 5 and 6).

Figure 5.

Radiographs taken 3 months following fixation with the use of a fibular strut allograft to improve bony purchase.

Figure 6.

Radiographs taken 12 months following fixation with the use of a fibular strut allograft.

This case demonstrates a novel approach to treating distal humerus fractures in a patient with osteoporosis with the use of a fibular strut allograft to aid in dual plating. We do not believe that all patients with osteoporosis will need an allograft. Rather, we feel it is important to have this option available if bony purchase is recognized to be less than adequate. Further research is necessary to identify which patients will benefit from an allograft (preoperatively). Potentially, parameters (preoperatively determined) such as T score, cortical thickness, or fracture architecture may serve as indicators for the use of strut allograft. Further research in this field may result in important information regarding more specific indications and benefits for this procedure.