Clinical Outcome After Replacement of Distal Femur/Proximal Tibia in a Heterogeneous Patient Cohort: Function Following Tumour, Trauma, and Loosening

Abstract

Background: Distal femur and proximal tibia replacements as limb-salvage procedures with good outcome parameters for patients with tumours have been broadly described. However, the overall midterm outcome in a mixed, heterogeneous patient collective is still unclear. Patients and Methods: We retrospectively analysed 59 consecutive patients (33 for primary and 26 for revision surgery) between 1998 and 2017. Indication for implantation was tumour (n=16), periprosthetic fracture (n=14), traumatic fracture (n=14), infection (n=10), aseptic loosening (n=3), and pathological fracture (n=2). The mean follow-up duration was 3 years. Clinical functions were evaluated by Toronto Extremity Salvage Score and Knee Society Score. Knee extension and flexion force were measured. Results: The overall survival rate of arthroplasties was 59% (n=35). Major complications were observed in 36 (61%) patients. During the follow-up period, 14 (24%) patients died. We recorded periprosthetic joint infection in 21 (36%) patients, recurrence of tumour in two (3%), and aseptic implant failure in three (5%). The mean Toronto Extremity Salvage Score was 66±33, and the mean Knee Society Score was 49±30. The mean extension force on the operated side was significantly reduced at 60å nd 180˚ compared to the healthy side (p=0.0151 and p=0.0411, respectively). Conclusion: Distal femur and proximal tibia replacements showed limited clinical function in a heterogeneous patient collective. Indication for implantation should be considered carefully.The overall numbers of mega-arthroplasties are increasing. Although clinical function and patient reported outcomes after primary total knee arthroplasty are well described, existing data on revision arthroplasty, such as replacement of the distal femur and proximal tibia, are rare. Indications for revision surgery/patient-specific mega-arthroplasty at the knee are: (i) Primary implantation such as arthroplasty in cases of large bony defects after tumour resection or primary complex fracture; and (ii) revision surgery after failed total knee arthroplasty in cases of aseptic and septic loosening, periprosthetic fracture, pseudarthrosis, or recurrent prosthetic instability (1-4). The incidence of periprosthetic fractures with large bone defects range between 0.3% and 5.5% after primary total knee arthroplasty and are seen in up to 30% cases after revision arthroplasty, with mortality rates as high as 46% (1, 5).At our clinic, we primarily use the Modular Universal Tumour and Revision System (MUTARS ® ) (Implantcast GmbH, Buxtehude, Germany) for large bony defects at the distal femur and proximal tibia, which is a well-established system (6). The stem is made of titanium alloy (TiAl6V4) in the cementless implant and of CoCrMo alloy in the cemented version (1). Although good leg-length alignment and good clinical function can be achieved, implantation is associated with high reoperation rates of 25-50% (1, 3, 5-7). The opportunity to return to daily living after distal femur/proximal tibial replacement is impaired ...

Clinical outcomes of cemented distal femur replacements with all-polyethylene tibial components for oncologic indications

“…In total, 20 patients (36.4%) experienced a postoperative complication requiring reoperation (Figure 4 ). The indications for the 26 reoperations were the following: Mechanical failure[ 11 ], non-union of prior pathological fracture[ 7 ], tumor progression[ 3 ], definitive management of a prior open reduction internal fixation for a pathologic fracture[ 2 ], local recurrence[ 1 ], infection[ 1 ], and soft tissue failure[ 1 ] (Table 4 ). Of these 20 cases requiring reoperation, 7 patients (12.7%) required only one reoperation, 2 patients (3.6%) required 2 reoperations, 4 patients (7.3%) required 3 reoperations, and 7 patients (12.7%) required 4+ reoperations.…”

“…However, there is a paucity of literature examining the survivorship of distal femoral replacements (DFRs) with respect to the type of tibial component or fixation used[ 8 , 9 ]. Furthermore, the majority of available studies fail to describe the type of tibial component or fixation used[ 10 , 11 ]. Therefore, the purpose of this study is to assess outcomes of cemented DFRs with all-polyethylene tibia (APT) components used for oncologic indications.…”

CORR Insights®: What Factors Are Associated With Stem Breakage in Distal Femoral Endoprosthetic Replacements Undertaken for Primary Bone Tumors?

“…This “chicken and egg” situation results in the need for surgeons to carefully monitor bony ingrowth on porous body components, to consider press-fit stems or line-to-line reaming when cementing into narrow femoral canals, and to work with implant companies to provide larger-diameter stems for all reconstruction situations. Because stem breakage is rare, it is important for future studies to replicate the findings of this study [6], and perhaps identify other potential causes for stem fractures, so that we can develop strategies to prevent this disastrous result.…”

“…There are several theories as to the causes of stem breakage in distal femur endoprosthetic reconstructions. Aseptic loosening owing to loosening at the bone-implant interface can lead to implant instability and eventually stem fracture [6,9]. Periprosthetic fractures around tumor prostheses caused by trauma or osteoporotic bone can also result in intramedullary stem breakage [13].…”