A Review Paper Primary Total Knee Arthroplasty for Distal Femur Fractures: A Systematic Review of Indications, Implants, Techniques, and Results Foster Chen, MD, Robert Li, MD, Ajay Lall, MD, and Evan M. Schwechter, MD Abstract Distal femur fractures (DFFs) in elderly EMBASE (Excerpta Medica dataBASE), and patients historically were difficult to treat the Cochrane Library. Few studies of this because of osteoporotic bone, comminution, technique have been reported, and the ma- and intra-articular involvement. Current jority of published studies have been level surgical treatment options, including III and level IV, with heterogeneous results intramedullary nailing, internal fixation, and outcomes. Many of the patients in these and external fixation, are complicated studies achieved early weight-bearing with by prolonged immobility, malunion, and primary TKA. Complication rates varied and nonunion. Furthermore, fixation increases may be higher for older patients with more the complexity of subsequent arthroplasty. comorbidities, but whether these rates are Primary total knee arthroplasty (TKA) is a higher than those of patients treated with rarely used treatment for acute DFF but may internal fixation is unclear. be of benefit in select patients. Modular constrained implants may be ap- For a systematic review of the reported propriate for comminuted intra-articular frac- indications, techniques, implants, out- tures, whereas extra-articular fractures may comes, and complications of TKA for DFF, be sufficiently managed with unconstrained we searched the major databases Medline, implants supplemented with fracture fixation. istal femur fractures (DFFs) in the elderly historically were difficult to treat because Take-Home Points of osteoporotic bone, comminution, and D ◾ Arthroplasty is a rarely utilized and, therefore, a rarely reported intra-articular involvement. DFFs in minimally am- treatment for distal femur fractures. bulatory patients were once treated nonoperative- ly, with traction or immobilization,1,2 but surgery ◾ Arthroplasty carries certain advantages over fixation, including earlier weight-bearing, a benefit for elderly individuals. is now considered for displaced and unstable fractures, even in myelopathic and nonambulatory ◾ Arthroplasty is more often described in situations of patients, to provide pain relief, ease mobility, and comminution, often necessitating constrained prostheses. decrease the risks associated with prolonged bed ◾ It is not unreasonable to utilize arthroplasty in extra-articular rest.1 Options are constantly evolving, but poor fractures in poor-quality bone, which can take the form of knee function, malunion, nonunion, prolonged unconstrained prosthesis and supplemental fixation. immobilization, implant failure, and high morbidity ◾ The true complication rate is unclear, given that the few papers and mortality rates have been reported in several reporting high complication rates were in sicker populations. studies regardless of fixation method. Authors’ Disclosure Statement: The authors report no actual or potential conflict of interest in relation to this article. www.amjorthopedics.com May/June 2017 The American Journal of Orthopedics ® E163 Primary Total Knee Arthroplasty for Distal Femur Fractures Arthritis after DFF has been reported at rates of ies regarding nonacute (>3 months or nonunion) 36% to 50% by long-term follow-up.3-5 However, DFFs or periprosthetic fractures, or studies that total knee arthroplasty (TKA) for posttraumatic considered only treatments other than TKA (ie, arthritis is more complex because of scarring, ar- plate osteosynthesis). throfibrosis, malunion, nonunion, and the frequent Full-text publications were obtained and inde- need for hardware removal. These cases have a pendently reviewed by Dr. Chen and Dr. Li for higher incidence of infection, aseptic loosening, relevance and satisfaction of inclusion criteria. stiffness,6 and skin necrosis.7 Disagreements were resolved by discussion. Primary TKA is a rarely used treatment for acute Given the rarity of publications on the treatment, all DFF. Several authors have recommended prima- study designs from level I to level IV were included. ry TKA for patients with intra-articular DFFs and The same 2 reviewers extracted the data into preexisting osteoarthritis or rheumatoid arthritis, prearranged summary tables. Data included study severe comminution, or poor bone stock.7-22 Com- size, patient demographics, AO/OTA (Arbeits- pared with open reduction and internal fixation gemeinschaft für Osteosynthesefragen/Ortho- (ORIF), primary TKA may allow for earlier mobility paedic Trauma Association) fracture type either and weight-bearing and thereby reduce the rates reported or assessed by description and imaging of complications (eg, respiratory failure, deep vein (33A, extra-articular; 33B, partial articular with 1 thrombosis, pulmonary embolism) associated with intact condyle; 33C, complete articular with both prolonged immobilization.23 condyles involved), baseline comorbidity, implant As the literature on TKA for acute DFF is scant, used and fracture treatment (if separate from and to our knowledge there are no clear indica- arthroplasty), postoperative regimen, respective tions or guidelines, we performed a systematic re- outcomes, and complication rates. view to determine whether TKA has been success- ful in relieving pain and restoring knee function. Results In this article, we discuss the indications, implant We identified 728 articles: 389 through Med- options, technical considerations, complications, line, 294 through EMBASE, and 45 through the and results (eg, range of motion [ROM], ambulato- Cochrane Library (Figure 1). After duplicates ry status) associated with these procedures. were removed, 476 articles remained. After titles and abstracts were reviewed, 22 articles met the Methods screening criteria. Five series included patients On December 1, 2015, we searched the major with TKA-treated acute DFF but did not report their databases Medline, EMBASE (Excerpta Medica specific outcomes (these were described sepa- dataBASE), and the Cochrane Library for articles rately). published since 1950. In our searches, we used The current evidence regarding primary TKA for the conjoint term knee arthroplasty with femur acute DFF is primarily level IV (Table 1). Only 1 level fracture, and knee replacement with femur III study16 compared TKA with ORIF. Three case fracture. Specifically, we queried:((“knee replace- series11,19,24 met our inclusion criteria (Table 1, ment” OR “knee arthroplasty”) AND (intercondy- Table 2). In addition, 5 case series involved pa- lar OR supracondylar OR femoral OR femur) AND tients who met our criteria, but these studies did fracture) NOT arthrodesis NOT periprosthetic NOT not separately report results for DFFs and proximal “posttraumatic arthritis” NOT osteotomy. We also tibia fractures,9,20-22 or separately for acute fractures hand-searched the current website of JBJS [Jour- and nonunions or ORIF failures.8 These studies nal of Bone and Joint Surgery] Case Connector, a were considered level IV and were tabulated sep- major case-report repository that was launched in arately (Table 3). Specific patient characteristics 2011 but is not currently indexed by Medline. and management strategies varied significantly All citations were imported to RefWorks for between studies, though many studies augmented management and for removal of duplicates. Each 33A fractures with internal fixation, whereas 33C article underwent screening and review by Dr. fractures more often underwent resection and Chen and Dr. Li. Articles were included if titles placement of highly constrained implants. Of 117 were relevant to arthroplasty as treatment for acute DFFs reviewed, 20% were 33A fractures, acute (within 1 month) DFF. Articles and cases 7% were 33B fractures, and 73% were 33C frac- were excluded if they were reviews, published in tures (Table 1). Of the studies that specified, there languages other than English, animal studies, stud- were 8 cases of rheumatoid arthritis and 18 cases E164 The American Journal of Orthopedics ® May/June 2017 www.amjorthopedics.com F. Chen et al JBJS CC, BJJ, Acta, Medline EMBASE Cochrane Library JA, JOT, IO 389 294 45 0 476 articles after duplicates removed 476 records screened for titles 454 articles excluded for relevance and abstracts 3 reviews excluded for lack of proper treatment acuity 1 non-English article excluded 22 articles relevant 5 articles excluded for including arthroplasty as treatment for acute DFF but not specifically reporting outcomes (included for discussion) 13 articles met inclusion and exclusion criteria Figure 1. PRISMA (Preferred Reporting Items for Systematic Reviews and Meta-Analyses) flow diagram showing method of article selection. Abbreviations: Acta, Acta Orthopaedica; BJJ, Bone & Joint Journal (previously Journal of Bone & Joint Surgery-British); DFF, distal femur fracture; EMBASE, Excerpta Medica data- BASE; IO, International Orthopaedics; JA, Journal of Arthroplasty; JBJS CC, Journal of Bone & Joint Surgery Case Connector; JOT, Journal of Orthopaedic Trauma. of osteoarthritis (Table 2). cannulated screws, Dall-Miles cabling (Stryker), and Modular, hinged, and tumor-type arthroplasty plate osteosynthesis. Choi and colleagues19 took a designs accounted for 83% of the treatments similar approach but also used stem extensions in included in this review. Trade names are listed in 6 of 8 fractures assessed to be unstable (Figures Table 4. Authors