In five ankles, screws were placed in the distal fragment to help to maintain length. After fixation was achieved, fibular length was again confirmed radiographically by visualization of the fibular fracture fragments and by comparison with the other ankle. In particular, the talocrural angle was used to confirm the accurate restoration of fibular length and the congruence of the ankle mortise (Fig. 3)9. Additionally, the medial clear space and the tilt of the talus in the mortise were compared between sides. If intraoperative evaluation following lateral fixation demonstrated that the syndesmosis was unstable, syndesmotic screws were placed through the plate, which acts as a substitute lateral cortex in order to stabilize the syndesmosis (Figs. 4-A and 4-B). If the medial injury was ligamentous, instability was identified by measuring the medial clear space and the syndesmotic space or by identifying any lateral subluxation of the talus radiographically with the application of an abduction stress on the ankle. If medial fixation had been performed, then a laterally directed force was applied with use of a clamp placed on the fibula to test for syndesmotic instability, which was defined as the occurrence of >2 mm of lateral translation of the fibula with respect to the tibia at the syndesmotic notch with the foot held in a neutral position. If syndesmotic fixation was placed, the patient was given the option of removal at a minimum of three months. There was no attempt to reduce the comminuted fibular fracture fragments. The plate simply spanned the comminution of the fibula, analogous to “bridge plating” in other long bones10. No bone-grafting was performed. All patients were managed with a cast postoperatively and were kept nonweight-bearing.
The study group included sixteen men and fifteen women with an average age of forty-four years (range, nineteen to seventy-six years). The average time for fibular fixation was sixteen minutes (range, ten to thirty-two minutes) from incision to fixation. There were nineteen bimalleolar fractures (OTA type 44C2.2) and twelve lateral malleolar fractures with an associated deltoid ligament injury (OTA type 44C2.1). Eighteen patients had medial-sided fixation, and twenty-three (including fourteen of the nineteen with a bimalleolar fracture and nine of the twelve with a lateral malleolar fracture) had placement of syndesmotic screws. One patient with an anterior collicular fracture and poor medial skin had nonoperative treatment of a medial malleolar fracture, which went on to a painless, fibrous union.
Immediately postoperatively, all patients had a well-aligned mortise on the fractured side as compared with the normal side on the basis of measurements of the medial, superior, lateral, and syndesmotic spaces, the position of the fibula on the lateral view, and the talocrural angle (which measured within 2° of that on the normal side). All fibular fractures healed without displacement within ten weeks. One patient was lost to follow-up after fracture union had occurred. Of the remaining thirty patients, twenty-one were followed for a minimum of two years (average, 2.3 years; range, two to four years). The average American Orthopaedic Foot and Ankle Society (AOFAS) score for these patients at the time of the latest follow-up was 82 (range, 68 to 100)11. The range of motion averaged 13° of dorsiflexion and 31° of plantar flexion, with one patient having a fixed plantar flexion contracture of 5° (this patient did not return for follow-up for four months and was undergoing a course of serial casting at the time of the most recent follow-up). There were no deep infections, but one elderly patient with type-1 diabetes had minor superficial skin breakdown that healed without operative intervention.
Unstable stage-3 pronation-abduction ankle fractures result in laterally comminuted fibular shaft fractures because of the bending moment at the time of fracture. The resultant fragmented bone is challenging to adequately align while maintaining satisfactory vascularity for fracture-healing. A classic direct open fracture reduction and rigid plate fixation will violate the soft-tissue attachments of the fragments and jeopardize the viability of the injured bone12,13. The surgical site is therefore placed at risk for nonunion and infection.
Because the endosteal blood supply is interrupted in association with a comminuted shaft fracture, the vitality of the bone depends on the periosteal vasculature and adjacent musculature, as does fracture-healing. One way to obtain stability while protecting the soft tissue is to apply a plate outside of the periosteum13,14, spanning the fracture fragments, to function as an internal splint. This technique provides stability at the fracture site similar to the level of fixation provided by an intramedullary nail or a cast. It allows micromotion at the fracture site but does not violate the delicate biology necessary for bone-healing; therefore, interfragmentary callus forms and the fracture proceeds to union14,15.
Indirect reduction techniques imply that the fracture site is not directly violated and therefore its soft-tissue envelope remains mostly intact. Ligamentotaxis and utilization of a plate as a reduction tool can be used to assist with the less invasive reduction in order to obtain stable fixation6.
These concepts have been explored extensively in association with femoral fractures. In studies involving cadaveric femora, Farouk et al.16,17 showed that minimally invasive plate osteosynthesis was superior to conventional plate osteosynthesis for preserving arterial femoral vascularity and perfusion. Other investigators have shown that union through callus formation, similar to that achieved with intramedullary fixation, can be obtained safely with a decreased need for bone-grafting and a decreased risk of infection through this minimally invasive, submuscular plating technique7,8,18. This concept has been applied to long-bone fractures of the femoral shaft as well as to periarticular and intra-articular fractures of both the femur7,8 and the tibia19.
In 1987, Limbird and Aaron5 reported on a series of eight laterally comminuted ankle fracture-dislocations in which anatomic reduction of the mortise and restoration of fibular length had been difficult to achieve secondary to discontinuity of the fibula. All of the patients underwent traditional open reduction and internal fixation, which included stripping the periosteum and opening the fracture site. The authors identified comminution of the distal part of the fibula as the cardinal feature of the injury but also reported that the anterior tibiofibular ligament was torn in all cases. Bone-grafting of the fibular defects was performed in six of the eight patients. The two fractures that did not receive bone graft went on to nonunion and required further revision surgery with secondary bone-grafting. These injuries were consistent with a pronation-abduction pattern ankle fracture. Similarly, Ebraheim et al.4 reported on nine Weber type-C, stage-3 pronation-abduction ankle fractures that were treated with traditional open reduction and internal fixation. Five required syndesmotic fixation. There was one delayed union and one nonunion. Those authors also recommend bone-grafting for high-energy fractures with comminution.
In the current series, after stabilization of the medial osseous injury (when present), a precontoured plate was placed directly laterally outside of the periosteum, spanning the area of fracture comminution, similar to a bridge plate. The direct lateral location opposes the abduction moment that caused the original injury. The extraperiosteal position precludes the need for bone graft, decreases the risk of infection, and provides the most biologically friendly environment for union. Also, using the plate as the reduction tool allows the softtissue envelope to be preserved while still allowing appropriate length and alignment to be obtained. All fractures in the present series exhibited a well-aligned mortise and went on to union without bone-grafting.
In 1978, Pankovich20 described a series of ankle fractures that included fourteen pronation-abduction injuries (five of which were stage 2 and nine of which were stage 3). Fixation of the medial side only did not restore stability in the patients with stage-2 injuries, and all required syndesmotic fixation. Six of the nine patients with a stage-3 fracture had persistent instability of the ankle after plating of the fibula and required syndesmotic fixation. Eleven of these fourteen patients achieved a painless ankle with a normal or nearly normal range of motion. In the current series, the syndesmosis was stressed after lateral fixation was completed21. When necessary, syndesmotic screws were placed directly through the plate. In such cases, the lateral plate serves as a substitute lateral cortex, which adds greater strength to the syndesmotic fixation as these screws often traverse the comminuted area of the fibula.
The technique of extraperiosteal plating of pronation-abduction fibular fractures has been described previously22. A lateral buttress plate, usually applied outside of the periosteum, bridges the comminuted fragments. The concept of indirect reduction with use of a plate also has been described for the treatment of high fibular fractures associated with a syndesmotic injury22. With this technique, distal fixation is performed first and then the fibula is subsequently pushed out to length before the proximal screws are placed. We prefer to perform proximal fixation first because manipulation of the foot combined with medial fixation, when necessary, generally restores fibular length, obviating the need for distal fibular fixation in most cases. The plate acts as a push plate, reducing the fibula and centering the talus within the mortise. In our series, only five of the thirty-one fractures required distal fibular fixation to maintain length.
There is only limited information regarding the outcomes of unstable ankle fractures. Lindsjo23 reported unlimited functional ability to work in 90%, to do physical activity and play sports in 82%, and to walk in 89% of patients in that series, as well as good range of motion, after surgical treatment of ankle fractures. In a retrospective review in which patients with operatively treated ankle fractures were compared with a group of control subjects, Belcher et al.24 reported functional impairment at eight to twenty-four months postoperatively despite adequate reduction and no radiographic evidence of degenerative changes; however, the study did not address whether these differences significantly impacted the patients' quality of life. Obremskey et al.25 observed that although patients continue to show improvement in function for as long as twenty-four months after surgical fixation, residual physical and functional effects can be expected. The degree to which these residual effects impact the quality of life is low. These reports are consistent with our findings, as all of our radiographs revealed osseous union with a well-aligned mortise and a stable joint and all patients but one had good range of motion.
In the present series, we found extraperiosteal plating to be an effective method for the stabilization of pronation-abduction ankle fractures. The technique allows for accurate reduction of the mortise without stripping the periosteum of the comminuted region of the fracture. In contrast with previous work, bone-grafting was not used and yet all fractures healed. The outcomes were similar to those in other series of ankle fractures after open reduction and internal fixation4,20,23,26, although we believe that the present study represents the first series that has been limited to only pronation-abduction injuries. The technique is easier and faster than standard techniques in which the lateral periosteum is split to facilitate placement of the plate. We recommend this technique for the treatment of comminuted pronation-abduction ankle fractures. Medial fixation, specific attention to restoring the length of the fibula and the fibular position as seen on the lateral radiograph, and evaluation of the syndesmosis after fibular fixation are essential elements of the technique. ▪
Disclosure: The authors did not receive any outside funding or grants in support of their research for or preparation of this work. Neither they nor a member of their immediate families received payments or other benefits or a commitment or agreement to provide such benefits from a commercial entity. A commercial entity (Smith and Nephew) paid or directed in any one year, or agreed to pay or direct, benefits in excess of $10,000 to a research fund, foundation, division, center, clinical practice, or other charitable or nonprofit organization with which the authors, or a member of their immediate families, are affiliated or associated.
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Investigation performed at the Department of Orthopaedic Surgery, Boston University Medical Center, Boston, Massachusetts
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