Objectives

Venous thromboembolism (VTE) is a major potential complication following orthopaedic surgery. Subcutaneously administered enoxaparin has been used as the benchmark to reduce the incidence of VTE. However, concerns have been raised regarding the long-term administration of enoxaparin and its possible negative effects on bone healing and bone density with an increase of the risk of osteoporotic fractures. New oral anticoagulants such as rivaroxaban have recently been introduced, however, there is a lack of information regarding how these drugs affect bone metabolism and post-operative bone healing.

The aim of this study was to analyse the gait pattern, muscle force and functional outcome of patients who had undergone replacement of the proximal tibia for tumour and alloplastic reconstruction of the extensor mechanism using the patellar-loop technique.

Between February 1998 and December 2009, we carried out wide local excision of a primary sarcoma of the proximal tibia, proximal tibial replacement and reconstruction of the extensor mechanism using the patellar-loop technique in 18 patients. Of these, nine were available for evaluation after a mean of 11.6 years (0.5 to 21.6). The strength of the knee extensors was measured using an Isobex machine and gait analysis was undertaken in our gait assessment laboratory. Functional outcome was assessed using the American Knee Society (AKS) and Musculoskeletal Tumor Society (MSTS) scores.

The gait pattern of the patients differed in ground contact time, flexion heel strike, maximal flexion loading response and total sagittal plane excursion. The mean maximum active flexion was 91° (30° to 110°). The overall mean extensor lag was 1° (0° to 5°). The mean extensor muscle strength was 25.8% (8.3% to 90.3%) of that in the non-operated leg (p < 0.001). The mean functional scores were 68.7% (43.4% to 83.3%) (MSTS) and 71.1 (30 to 90) (AKS functional score).

In summary, the results show that reconstruction of the extensor mechanism using this technique gives good biomechanical and functional results. The patients’ gait pattern is close to normal, except for a somewhat stiff knee gait pattern. The strength of the extensor mechanism is reduced, but sufficient for walking.

Cite this article: Bone Joint J 2015;97-B:1063–9.

Introduction: Surgical treatment options of malignant tumors of the pelvis were traditionally very limited, and often resulted in an amputation. With development of neo/-adjuvant therapies, limb-salvage surgery has become the treatment of choice. Still, the treatment remains challenging, and options for pelvic reconstruction after resection such as allografts, radiated autografts, saddle-prosthesis, custom made prosthesis and modular reconstruction systems are all associated with high complication rates. Aim of our retrospective study was to evaluate the results after reconstruction of the pelvis with a custom-made pelvic megaprosthesis.

Materials and Methods: From 1977 to 2008, a total of 92 patients with malignant tumors or metastases of the pelvis were treated by resection and reconstruction with custom-made pelvic megaprostheses at our institution. Mean age was 56.2 years [17–77] with 43 male patients and 59 female. We treated 45 primary tumors and 47 metastases. Primary tumors included chondrosarcoma (45,4%), Ewing’s sarcoma (18,2%), malignant fibrous histiocytoma (9,1%), osteosarcoma (4,5%) and others. In the group with metastases we found renal cell carcinoma (52,4%), mamma-carcinoma (14,3%), thyroid carcinoma (9,5%), oropharyngeal carcinomas (9,5%), and others. Wide resection was performed in 11 patients, marginal-resection in 47, and intralesional-resection in 34 patients. Depending on the bone defect after tumor resection, pelvic megaprostheses were implanted either in the superior part of the iliac wing, the sacrum and/or the lower lumbar spine.

Results: Patients were reassessed repeatedly at two different time points resulting in a mean follow-up of 3,6 years [range 0,5 to 8,4years]. A total of 55 patients were available for follow-up, 29 had died and 6 Patients were not available for evalutation (living abroad). In the group with malignant tumors 50% of the patients were alive after 5 years; 50% of patients with metastasis survived at least 2 years. The local recurrence rate was 15%. In 2 of these patients local re-resection was possible, and 5 patients were treated with secondary external hemi-pelvectomy. Aseptic failure of the megaprosthesis was observed in 3%. The MSTS-Score showed good results in 34%, fair results in 42% and poor results in 23%. We found infections in 14%. Nerve palsy occurred in 11%, thombosis in 5%, and dislocation of the prosthesis in 15% of patients.

Discussion: Our study demonstrates that reconstruction of pelvic bone defects after tumor resection with custom-made megaprosthesis allows limb-salvage surgery with satisfying functional results. In spite of the relatively high complication rates-which are comparable or even favorable to other reconstruction techniques-we consider the custom-made megaprosthesis our treatment of choice to reconstruct pelvic bone defects.