Discussion
DFFs in the elderly historically were difficult to treat. Reported outcomes are largely favorable, but, even with newer plate designs, catastrophic failures still occur in the absence of bony union.26,27 After ORIF, patients’ weight-bearing is often restricted for 12 weeks or longer28—a protocol that is undesirable in elderly patients, especially given that the rate of mortality 1 year after these fractures has been found to be as high as 25%.29
Arthroplasty for DFFs—performed either with ORIF, or independently with a constrained implant—is a documented treatment modality, but the evidence is poor, and results have been mixed. Patients who received hinged TKA with major fracture resection had higher complication rates.8,11,22,24 However, the problems were mostly medical, not associated with surgical technique. Appleton and colleagues24 found a higher than expected 1-year mortality rate, 41%, but used an unhealthy baseline population (44% cognitive impairment, 17% nonambulatory before injury).Although Boureau and colleagues22 found a 1-year mortality rate of 30%, only 1 in 10 deaths was attributable to a perioperative complication. Among the remaining cases involving resection and megaprostheses for previously ambulatory patients, only 1 perioperative death was recorded (Table 2).11,12,16,18 Therefore, the risks associated with patients’ baseline health and ambulatory status must be weighed against the benefits of aggressive arthroplasty.
An overwhelming majority of 33C fractures were treated with megaprostheses—a finding perhaps attributable to the higher likelihood that patients with osteoporosis have intra-articular, comminuted injuries. In addition, surgeons may have been more likely to indicate 33C fractures for joint replacement, whereas 33A and 33B patterns were more amenable to fracture fixation.17,18 Interestingly, few type B fractures (0 in primary analysis and only 9 of 67 cases in Table 3) were treated with megaprostheses. In these situations, 1 condyle and ligamentous constraint remain intact, reducing the need for a constrained implant.
There were no reports of atraumatic or aseptic loosening, though use of rotating platforms with linked prostheses helps minimize this complication. Also surprising is the lack of nonunions in any of the reviewed studies, as nonunion is one of the most devastating complications of ORIF. Only 1 superficial and 2 deep infections were reported in all of the literature—representing 1.8% of all cases, which is comparable to the rate for elective primary TKA.30In elderly patients with significant comorbidities, the main surgical goals are to minimize operative time and reduce time to mobility. It is therefore imperative to keep in mind that arthroplasty is elective. However, functional results of primary TKA for DFF may be more encouraging for healthier patients, as many can achieve satisfactory ROM and early weight-bearing. Therefore, TKA for DFF may benefit healthy and ambulatory patients in the setting of intra-articular comminution. Whether this treatment affects mortality rates remains to be seen.
There were several limitations to this study. First, the literature on the topic is scant. Second, exclusion criteria were kept lax to allow for inclusion of all treatments. This came at a cost to internal validity, given the heterogeneous population and differences in comorbidities between studies. Fracture classification was inconsistent as well: Although AO/OTA classification was dominant, descriptive classifications were used in several cases7,10,12 (these descriptions, however, were sufficient for assigning equivalent AO/OTA classes). Details on preoperative functional status and comorbidity status and on postoperative protocols were also limited, though ROM and ambulatory status were provided in most studies. Last, most of these studies were single case reports or case series, so there may be reporting bias in the body of the literature, as reflected in the discrepancies between encouraging case reports and concerning case series with longer follow-up. Such bias can be avoided with larger, controlled sampling and adequate follow-up.
TKA should be considered for acute DFF in patients who have knee arthritis and are able to tolerate the physiological load of the surgery. In the choice of implant design, several factors should be considered, including bone quality, articular involvement, degree of comminution, and ligamentous injury. Unconstrained knee designs should be considered in cases in which the fracture pattern appears stable and the collateral ligaments are intact (eg, 33A and 33BB fractures). Megaprostheses, which may allow for immediate weight-bearing but require considerable bone resection, would be beneficial in 33C fractures and in fractures with ligamentous compromise. However, their complication rates are unclear, and comparative studies are needed to investigate whether the rates are higher for these patients than for patients treated more traditionally.
Am J Orthop. 2017;46(3):E163-E171. Copyright Frontline Medical Communications Inc. 2017. All rights reserved.