case_images: PMC4079896_01
case_images: Implant loosening due to periendoprosthetic tibial chondrosarcoma. Anterior-posterior (a) and lateral (b) radiograph prior to total knee arthroplasty (TKA) depicting medial joint space narrowing and meniscal calcification. A radiolucent lesion in the central tibial plateau is indicated by a red arrow. Lateral (c) and anterior-posterior radiograph (d) 14 month after TKA surgery showing the osteolytic lesion in the proximal tibia, extending through the epi- and metaphyses from the central region to the lateral and anterior cortical bone. Permeation of the cortical bone with discontinuing periosteal reactions, including spiculae formation, can be observed. Preoperative planning was performed to determine plains of resection at 8 cm proximally and 15 cm distally to the joint line (indicated by red lines in c and d). Local CT-scans are showing cortical bone permeation, especially in the anterior and lateral aspects of the proximal tibia at the level of the cemented tibial implant (e) and below (f). Open incision biopsy was performed and multiple soft and bone tissue samples were obtained (g) and sent for microbiological and histopathological examination.
case_images: 40064_2013_1021_Fig1_HTML.jpg
case_images: PMC4079896_02_40064_2013_1021_Fig1_HTML.jpg
case_images: Fig1
case_images: This was then planned using the radiographs and CT-scans (Figure 1c-f), with the projected resections being located 8 cm proximal of the joint line at the femur and 15 cm distally of the joint line at the tibia.
case_images: PMC4079896_02
case_images: Implant loosening due to periendoprosthetic tibial chondrosarcoma. Anterior-posterior (a) and lateral (b) radiograph prior to total knee arthroplasty (TKA) depicting medial joint space narrowing and meniscal calcification. A radiolucent lesion in the central tibial plateau is indicated by a red arrow. Lateral (c) and anterior-posterior radiograph (d) 14 month after TKA surgery showing the osteolytic lesion in the proximal tibia, extending through the epi- and metaphyses from the central region to the lateral and anterior cortical bone. Permeation of the cortical bone with discontinuing periosteal reactions, including spiculae formation, can be observed. Preoperative planning was performed to determine plains of resection at 8 cm proximally and 15 cm distally to the joint line (indicated by red lines in c and d). Local CT-scans are showing cortical bone permeation, especially in the anterior and lateral aspects of the proximal tibia at the level of the cemented tibial implant (e) and below (f). Open incision biopsy was performed and multiple soft and bone tissue samples were obtained (g) and sent for microbiological and histopathological examination.
case_images: 40064_2013_1021_Fig1_HTML.jpg
case_images: PMC4079896_02_40064_2013_1021_Fig1_HTML.jpg
case_images: Fig1
case_images: This was then planned using the radiographs and CT-scans (Figure 1c-f), with the projected resections being located 8 cm proximal of the joint line at the femur and 15 cm distally of the joint line at the tibia.
case_images: Surgical management of periendoprosthetic tibial chondrosarcoma. A medial parapatellar approach was used for exposition, while the patellar-ligament was cut proximally, because of macroscopic suspected tumor infiltration (a). Medial subcutaneous preparation was performed carefully and pes-anserinus muscle insertions were secured for later reattachment (a). After the tibia was exposed 15 cm from joint line, tibial resection was performed as planned and detachment from the popliteal neurovascular structures was performed carefully, allowing en-bloc tumor resection. Because of suspicious marrow tissue a second tibial resection was performed 5 cm more distally (b), which resulted in R0 resection status. The femoral cut was performed as planned at 8 cm proximal to the joint line, to include the femoral component and match the planned femoral component of the revision implant (c). After marrow preparations and trialing, reconstruction of the extensor mechanism was prepared by creating a suprapatellar tunnel in the quadriceps tendon and implantation of an alloplastic ligament (d). Original components were cemented, using the prior tested sizes. Pes-anserinus and biceps-femoris tendons were reattached at the correspondent implant sites (e). The alloplastic ligament was secured with the screw-mechanism of the tibial implant and additional sutures (f). Drains were implanted distant to the tumor location and tension-free wound closure was performed (f).
case_images: 40064_2013_1021_Fig2_HTML.jpg
case_images: PMC4079896_02_40064_2013_1021_Fig2_HTML.jpg
case_images: Fig2
case_images: Resection steps included scar excision, resection of the inner part of the patella with complete patellar-tendon (Figure 2a), resection of the joint capsule under preservation of the muscle-insertions of the pes-anserinus (Figure 2a) and the biceps-femoris tendons. Resection was initially performed as previously planned as soft tissue structures were without signs of tumor infiltration. After en-bloc resection the distal marrow showed suspicious tissue, therefore the intraoperative decision to extent the resection 5 cm distally was made (Figure 2b), which resulted in macro- and microscopically tumor free margins. The femoral resection was performed as planned 8 cm proximal of the joint line to match the planned implant, while no suspect bone or soft tissue changes were observed at the resection margins (Figure 2c). After reposition and connection, the previously detached tendons were reattached using FiberWire   sutures (Arthrex, Naples, FL, USA), with reconstruction of the patellar tendon being performed using a Trevira synthetic ligament (Telos, Marburg, Germany) (Figure 2d-f), before tension free wound closure was performed.
case_images: PMC4079896_03
case_images: Soft tissue coverage following megaendoprosthetic knee reconstruction. Postoperative lateral (a) and anterioposterior (b) radiographs showing correct implant positioning. Due to the necessity of the patellar-ligament resection, absent soft tissue cover of the proximal anterior portion of the tibial implant caused wound-healing deficiencies, which required operative revisions (c). To achieve soft tissue coverage a medial gastrocnemius muscle flap was prepared (d) and covered with a mesh graft from the opposite thigh (e).
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case_images: PMC4079896_03_40064_2013_1021_Fig3_HTML.jpg
case_images: Fig3
case_images: While the postoperative radiographs (Figure 3a, b) showed correct implant positioning without signs of loosening or fracture, mobilization needed to be restricted due to delayed wound-healing over the site of patellar ligament-reconstruction, due to absent soft-tissue covering. This made operative wound revision necessary, including debridement (Figure 3c), gastrocnemius-flap-reconstruction (Figure 3d) in combination with a mesh-graft (Figure 3e) from the opposite thigh necessary.