The extracortical component of the prosthesis can be used for additional bone and soft tissue fixation in the form of a noose around the prosthesis. Bone struts, either autografts or allografts, are held circumferentially with Dacron tape to the prosthesis host bone interface (Fig 6). Theoretically, this procedure prevents debris from entering the bone cement interface, thereby reducing the possibility of aseptic loosening.18,31
If the greater trochanter was resected en bloc with the surgical specimen, the remaining abductor tendon is attached to the lateral aspect of the prosthesis through a metal loop with Dacron tape. If a fragment of the greater trochanter remains, it is fixed to the prosthesis with a cable grip system. Dynamic reconstruction is obtained by tenodesing the vastus lateralis to overlie the abductor muscle fixation. The remaining muscles are sutured to the vastus lateralis anteriorly and the hamstrings posteriorly (Fig 7).
The wound is closed over a 28-gauge chest tube that is attached to a continuous suction at 20 cm H2O. The patient's extremity is placed in balanced suspension or tibial pin traction with the hip elevated and flexed 20°.
The extremity is kept in balanced suspension for at least 5 days. An abduction brace is customized for the patient. Continuous suction is required for 3 to 5 days, and perioperative intravenous antibiotic therapy is continued until the drainage tubes are removed. Postoperative mobilization with an abduction brace and weightbearing as tolerated are continued for 6 weeks. Active hip abduction is required before the brace is removed and unprotected, full weightbearing allowed.
Fifty-seven patients with lesions of the proximal femur and midfemur underwent proximal or total femur resection. All had an intraarticular resection of the hip; the acetabulum was preserved and not resurfaced. Reconstruction devices included 38 modular, 12 custom made, and seven expandable prostheses with unipolar or bipolar heads. Table 2 summarizes the prostheses types used for reconstruction in the current series.
None of the patients had flap necrosis, nerve palsy, or thromboembolic complications. Deep wound infection necessitating surgical intervention occurred in two (3.5%) patients. Both were treated with repeated wound debridement and irrigations, delayed primary closure, and a regimen of intravenous antibiotics for 12 weeks after wound closure.
Dislocation occurred in one (1.7%) patient. This patient underwent proximal femur resection at 8 years of age, and reconstruction was performed with an expandable prosthesis. Dislocation occurred 58 months after surgery because of developmental acetabular dysplasia. The patient was treated with soft tissue reconstruction, and the prosthesis remained intact. Aseptic loosening occurred in three (5.2%) patients. Two of these patients had undergone proximal femur resection, and one had undergone total femur resection. Loosening occurred after 24 months; in the patient who underwent total femur resection, loosening occurred 14.7 years after surgery after a major trauma. All three loosenings occurred at the bone cement interface and required surgical revision.
Local recurrence developed in four of 46 (8.7%) patients with primary bone sarcomas, all of whom had a Stage IIB tumor at presentation.10 All recurrences occurred in the soft tissues. Three patients were treated with wide local excision with preservation of the prosthesis and adjuvant radiation therapy. Amputation was performed in the fourth. The limb salvage rate in the 46 patients with primary bone sarcomas was 98%. Table 3 summarizes the complications, indications for, and number of revision procedures, local recurrences, and functional outcome of the patients in this series.
All patients were ambulatory. None of the patients who underwent proximal femur endoprosthetic reconstruction required a walking aid (crutches, walker, or cane), and only three of the 18 (16%) patients who underwent total femur resection required such assistance. Trendelenburg test was positive in nine (16%) patients. Function was estimated to be good or excellent in 46 (81%) patients and fair in 11 (19%) patients. No difference in function was found between patients who underwent proximal femur replacement and those who underwent total femur replacement.
This article presents the surgical technique and outcome of proximal and total femur endoprosthetic reconstruction with an emphasis on joint stability, which is achieved by preservation of the acetabulum and reconstruction of the joint capsule and abductor mechanism.
The intracapsular location of the femoral neck makes it biologically possible for tumors of the proximal femur to spread into the hip and adjacent synovium, joint capsule, and ligamentum teres. The ligamentum teres provides a mechanism for transarticular skip metastases to the acetabulum. Fortunately, intraarticular involvement is rare and usually occurs after a pathologic fracture. The capsule can be preserved and an intraarticular resection of the femur can be performed in most cases. In the case of capsular or acetabular involvement or both, extraarticular resection of the hip is performed, and a saddle prosthesis may be used for reconstruction.1
All patients in the current series underwent intraarticular resection of the hip with preservation of the acetabulum. Hemiarthroplasty was used because of the increased likelihood of hip dislocation after acetabular resurfacing.32,33 Other major factors in stabilization are preservation of the hip capsule and capsulorrhaphy over the prosthetic neck and reconstruction of the abductor mechanism to the prosthesis.16,25,34
Hip abductors, which are attached to the greater trochanter, may be attenuated by an enlarging mass from the proximal femur but rarely are involved directly. It is important that these muscles be preserved after resection of most proximal femoral sarcomas because they are crucial to the soft tissue reconstruction, stability of the prosthetic replacement, and good functional outcome.24,30 There is a greater tendency for hip dislocation after massive proximal femur resection than after total hip arthroplasty, in which the abductor mechanism is preserved.3,24,25,32,33 Stability of the prosthesis is achieved further by balanced proximal traction by the abductors from the lateral aspect and the psoas muscle from the medial aspect. The psoas muscle is in close proximity to the anteromedial aspect of the hip; if a tumor enlarges anteriorly or posteromedially, a portion of this muscle may have to be resected. It is important that the remaining muscle be preserved for use in soft tissue reconstruction of the hip.24
Dislocation is the most common complication after proximal and total femur resection; rates range from 11% to 15%.15,16,24,30,34 In early series, in which capsular preservation was not emphasized, joint stability was based on muscle reconstruction and scar formation. Patients were placed in a long leg brace with a pelvic band or skeletal traction for 6 weeks to 5 months.3,21 Kabukcuoglu et al16 reported 54 patients who underwent proximal femur endoprosthetic reconstruction. In that series, an attempt was made to preserve the joint capsule, but the acetabulum was resurfaced, and no attempt was made to repair the hip abductors to the prosthesis; instead, they were sutured to the fascia lata.16 Those authors reported six (11%) dislocations, two of which necessitated surgical revision. Rechl et al24 reported 45 patients who underwent proximal femur endoprosthetic reconstruction. In that series, the abductor mechanism was reattached to the prosthesis in 41 of the 45 patients, but the acetabulum was resurfaced in all of them.24 Those authors reported seven (15.5%) dislocations.
In the current series, which emphasizes acetabular preservation, capsular repair, and anatomic reconstruction of the abductor mechanism, only one (1.7%) patient experienced a dislocation; it occurred almost 5 years after surgery and was secondary to acetabular dysplasia. Table 4 reviews the literature of dislocation rate after proximal or total femur endoprosthetic reconstruction; only series that include data on prosthesis type and technique of soft tissue reconstruction were included. The current series, which emphasizes the use of all three elements of hip reconstruction (acetabular preservation, capsulorrhaphy, and reconstruction of the abductor mechanism to the prosthesis), had the lowest dislocation rate.
There have been few reports on the longevity of proximal femur replacement prosthesis. Dobbs et al6 reported 81 patients who underwent proximal femur resection and reconstruction with a custom made prostheses. Event free survival rates were 73% and 63% at 5 and 10 years, respectively. Unwin et al29 reported a series of 263 patients who underwent proximal femur resection with endoprosthetic reconstruction. They reported a 93.8% probability that patients would not experience aseptic loosening during the 10 years after surgery.29 The favorable outcome of proximal femur replacements also was reported by Horowitz et al,13 who hypothesized a positive correlation between prosthetic survival and the availability of soft tissue for coverage.
The oncologic objective of proximal and total femur resections is to achieve local tumor control. Patient survival will be determined by the presence of metastatic disease and its response to adjuvant treatment modalities. Thus, the rate of local recurrence is the most appropriate criterion with which to evaluate the oncologic adequacy of proximal and total femur resections. Only four of the 46 (8.7%) patients in the current series who were treated for primary bone sarcomas had local recurrence of their disease, and only one patient required limb amputation. That rate is similar to that reported for tumors at the more common sites, such as the distal femur and proximal tibia, and is within the range expected after limb sparing procedures.23
The technique of acetabular preservation and hemiarthroplasty, Dacron tape capsulorrhaphy, and reconstruction of the abductor mechanism to the prosthesis significantly lowers the dislocation rate, which is the most common complication after proximal and total endoprosthetic reconstruction.
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