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 ...

Background/Aim: Patella baja (PB) and pseudopatella baja (PPB) have been shown to negatively influence outcomes after total knee arthroplasty. We hypothesized that there is a high incidence of PB and PPB after megaprosthetic total knee arthroplasty (M-TKA), and that this is associated with reduced range of motion. Patients and Methods: We retrospectively analysed all patients in our Orthopaedic Trauma Department after distal femur or proximal tibia replacement. Preoperative and one-year postoperative followup included measurement of range of motion and detection of PB and PPB using radiological indices. Results: We included 44 patients (age: 73±19 years). Preoperative PB detected by ISI could be reduced from 13 (36%) to 11 (25%) (p<0.01). Preoperative vs. postoperative ISI was 0.88±0.23 vs. 1.06±0.45 (p=0.03). PPB was observed preoperatively in 23 (63%) patients vs. 24 (54%) postoperatively. Preoperative vs. postoperative CDI was 0.70±0.24 vs. 0.95±0.43 (p=0.002). Preoperative flexion was 91˚±30˚ vs. 85˚±24˚ postoperatively (p>0.05). Conclusion: Both PB and PPB are frequently observed after M-TKA. A reduction in PB and PPB alone does not improve postoperative range of motion.

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Aims and Objectives: Mega-knee-arthroplasty are rare and indications are heterogeneous after fracture, tumour and infection. The outcome after distal femur- and/or proximal tibia replacement are unclear. We therefore wanted to analyse the postoperative outcome in case of primary and revision surgery. We hypothesize that I) Implantation of distal femur- and/or proximal tibia replacement are associated with reduced range of motion and function compared to the contralateral side and II) implantation in case of primary surgery is associated with better outcome than in case of revision surgery. Materials and Methods: We retrospectively analysed all patients in our trauma department between 1998 and 2017 who underwent a MUTARS distal femur replacement or proximal tibia replacement (Implantcast GmbH, Buxtehude, Germany). We collected general patients’ data, rang of motion, determined the Toronto extremity selvage score (TESS), musculoskeletal tumour society score (MSTS), knee society score (KSS) and Western Ontario MacMaster questionnaire (WOMAC) Score. Knee extension and flexion force was measured. Results: We included 59 patients with a mean age of 65+/-20 years. Out of these we had 19 (32%) male and 40 (68%) female patients. Mean follow up (f/up) was 36+/-57 month (range: 1-218). Indication for R-TKA was periprosthetic fractures (n=14), tumour (n=16), infection (n=10), traumatic fracture (n=14), aseptic loosening (n=3) and pathologic fracture (n=2). Indication for primary implantation was given in 33 (56%) patients and for implantation in case of revision surgery in 26 (44%) patients. Mean TESS was 66+/-33, mean MSTS was 14+/-7, mean KSS was 49+/-30, mean WOMAC was 36+/-26. Mean flexion on the operated side was 83°+/-24° compared to the healthy side (115°+/-20°) (p<0.001). Mean extension force on the operated side at 60° was 20+/-12 (Nm) compared to 77+/-58 (Nm) on the not operated side (p=0.31). Mean flexion force on the operated side at 60° was 32+/-26 (Nm) compared to 53+/-42 (Nm) on the not operated side (p=0.43). In case of revision surgery significant worse function scores in the TESS and KSS could be overserved (both p<0.05). Conclusion: Implantation of a distal femur- and/or proximal tibia replacement are associated with loss of flexion, a trend to reduced extension and flexion power compared to the contralateral side. In case of primary surgery better functional results in terms of function Scores can be expected than in case of revision surgery.