Abstract
Introduction: Allograft-Prosthesis Composite represents a reliable option for proximal femur replacement after resection for bone tumor. It provides advantages over megaprostheses because of better soft tissue repair and superior abduction strength, quality of gait, hip stability, and load transfer by healed bone rather than prosthetic stem, with potential impact on implant survival. Purpose of this paper was to review details of the surgical technique and results.
Methods: A retrospective study of 62 patients who had resection of the proximal femur because of a bone tumor and reconstruction with an Allograft-Prosthesis Composite was undertaken. The basic surgical technique consisted of an uncemented tapered long stem prosthesis (i.e. Wagner or Wagner-type stem) cemented in the allograft and press-fitted in the host bone, achieving bone-bone contact through a transverse osteotomy. Details of the surgical technique included: 1) accurate preoperative planning, canal sizing and implant selection; 2) under-reaming of the proximal 5–10 mm of the host medullary canal, depending upon bone quality and diameter of the selected stem; 3) allograft preparation and prosthesis cementation in the allograft; 4) introduction of the composite implant, pressfitted in host medullary canal, until bone-bone contact is achieved; 5) careful repair of abductors and iliopsoas to corresponding allograft tendon insertions.
Key points for successful fixation are absolute rotational stability and satisfactory circumferential bone-bone contact at the time of surgery.
Postoperative regimen consisted of hip, followed by progressive bracing and toe-touch weight-bearing for 6 weeks, weight-bearing.
Results: There were 2 septic failures. Two patients developed asymptomatic nonunion. There were no dislocations. Most common complication was fracture of the allograft greater trochanter (30%), which required surgery in only 1 case and never substantially affected function. The incidence of trochanteric fracture decreased from 63% in the first 27 patients to 5% in the following 35 patients by switching implant design from a valgus 145° neck angle to 135° neck angle, improving offset and abductors function. Bone grafting of the allograft-host union was required in 10% of the cases.
According to MSTS, results were satisfactory in 90% of the patients, with average score 91% (75%–96%).
Discussion and Conclusion: Allograft-Prosthesis Composite is a successful procedure for reconstruction of the proximal femur. Careful surgical technique is the key to excellent function and low complication rate.
Theses abstracts were prepared by Professor Roger Lemaire. Correspondence should be addressed to EFORT Central Office, Freihofstrasse 22, CH-8700 Küsnacht, Switzerland.
