Tumors extending into the pelvic cavity or buttock require the removal of the muscles that maintain hip joint stability, resulting in severe instability for hip prosthetic reconstruction. Constrained total hip prosthesis was developed in Japan for reconstruction after pelvic tumor resection and was easily fixed to the residual bone without restoration of pelvic continuity [10]. C-THA is composed of three parts (Fig. 11.2). The metallic outer head is fixed firmly with screws, bone cement, and bone grafting to the remaining ilium and sacrum. The inner head with a long neck and stem is cemented into the femoral shaft. These two components are connected by a high-density polyethylene-bearing insert, and the constrained total hip replacement is accomplished.

Reconstruction with the present C-THA model can lead to early rehabilitation due to immediate iliofemoral stabilization with a reduced risk of hip dislocation (Fig. 11.3). It is not necessary to reconstruct the pelvic ring disruption, resulting in a shorter operative time and fewer complications. Ueda et al. reviewed 25 patients treated with C-THA, demonstrating a mean MSTS (Musculoskeletal Tumor Society) functional score of 55 % and a 10-year implant survival rate of 67 % [11]. Major postoperative complications were seen in 32 %. They concluded that C-THA could provide pain-free hip reconstruction with immediate iliofemoral stability, suggesting this to be a useful reconstructive option for periacetabular tumors, despite serious postoperative complications.

The saddle prosthesis initially was designed by Nieder et al. in 1979 for large acetabular defects in revision hip arthroplasty [12]. Since the end of the 1980s, it has been used primarily for hip reconstruction after periacetabular tumor resection (Fig. 11.4) [13]. The largest series is from Aljassir et al. (27 cases), and the average MSTS score in their 17 living patients is 51 %, similar to functional results in other series [14].

The benefit of a saddle prosthesis includes stable limb reconstruction for early weight bearing, equal leg length, acceptable function, and relative ease of prosthesis placement compared to arthrodesis or allograft-prosthetic composites [15]. However, many design-related complications such as loosening, loss of motion, dislocation, and fractures have been addressed. In Japan, we have much less experience with saddle prosthesis, and there are only a few case reports available, which are published only in Japanese. Recent papers with a long-term follow-up period demonstrated that saddle prosthesis showed poor clinical and functional results, although it was a simple method of pelvic reconstruction that reduced surgical time [16, 17].

Various kinds of pelvic prostheses including custom-made or modular prosthesis have been reported in many countries [18–21], although reconstruction with pelvic megaprostheses was less popular for periacetabular tumors in Japan. Most papers regarding reconstruction with megaprostheses demonstrated that after good functional results in the beginning, the use of these mega-implants had a high complication rate: deep infection, dislocation, prosthesis loosening, broken screws, and prosthesis migration [2, 18, 19]. Due to its high complication rate, technical challenge, and implant expense, the concept of pelvic reconstruction has been changed. New types of pelvic replacement, such as “ice-cream cone” reconstruction or pedestal cup, were developed with promising early results [22, 23].

Reimplantation of recycled autograft has been a popular procedure for reconstruction following resection of bone and soft tissue sarcoma in Japan. Autografts have some advantages over allograft. Autografts do not contain foreign infectious or immunogenic agents. The fit at the host-graft junction and at the hip joint can always be perfect, and there is no need to maintain an extensive allograft bone bank. Since massive allografts such as pelvic bone are hardly available, surgical reimplantation of irradiated [24, 25], thermally heated [26, 27], and liquid-nitrogen-treated bones [28] has been widely accepted in Japan.

Reconstruction with pelvic recycled autobone and prosthesis could result in improved function (Fig. 11.5). However, this procedure has been associated with nonunion, bone absorption, and deep infection. The series of 15 patients with pelvic reconstruction using irradiated autobone demonstrated complications in 13 patients (87 %), including three deep infections [29]. Koyanagi et al. reported the long-term results of pasteurized autograft, demonstrating that three of four pelvic reconstructions resulted in deep infection; two of them were finally removed [30]. Jeon et al. reported 5- and 10-year survival rates of pasteurized bone to be 64 % and 32 %, respectively, in 14 patients with periacetabular tumor [31]. Yamamoto et al. reported a 33 % infection rate following pelvic reconstruction using frozen autograft [32]. Allograft and prosthesis composites have been popular procedures for periacetabular tumors in Western countries; [33–36] we believe that there is a little difference between long-term outcomes of recycled autobone and allograft.

Reimplantation of recycled autobone will inevitably only be indicated for a small proportion of patients with pelvic tumors. Jeon et al. suggested that first, ilioischial and iliopectineal lines should be intact radiologically, and second, the tumor should be small in volume [31]. According to Wafa et al. [37], the key indication is for the patient with a type I+II tumor which can safely be resected with clear margins and in whom the bone is of sufficient quality and solid enough to reimplant. Furthermore, since it would take up to a year to complete bone healing and regain function, this procedure should ideally be used in patients with a reasonable prognosis.

Iliofemoral and ischiofemoral arthrodeses have been employed successfully for many years in limb salvage for malignant pelvic tumors. The basic principle of arthrodesis is to obtain continuity of the hip with the residual pelvis, improving pelvic stability and weight-bearing potential. Fixation of the proximal femur or femoral head to the remaining ilium is performed using plates (Fig. 11.6). Patients with a solid fusion clearly showed a 71 % MSTS score [38]. The iliofemoral arthrodesis is the reconstructive option of choice for young and active patients with more activity requirements, because it is stable and durable.

Furthermore, iliofemoral or sacrofemoral arthrodesis using microsurgical fibula grafting has been reported [39, 40]. This technique restored continuity of the pelvic ring with minimal limb length shortening (Fig. 11.7), despite being a technical demanding procedure with a relatively long operative time.

An alternative to hindquarter amputation was reserving the leg after internal hemipelvectomy without reconstruction and leaving the remaining femur in place [41, 42]. Flail hip is at the opposite end of the spectrum of pelvic stability. Takami et al. demonstrated that the functional results of flail hip correlated with the amount of remaining ilium [43]. Schwartz et al. reported excellent results of flail hip with an average MSTS sore of 73 %, emphasizing the role of prolonged rehabilitation in its success [44]. Pseudoarthrosis may result as a failure after attempted fusion or an option of planned pseudoarthrosis, to preserve partial motion of the hip joint. Although the construct is less stable and the functional score is poorer than arthrodesis [38], pseudoarthrosis can maintain hip flexion, which is ideal for patients who sit more [22]. Surgical technique of hip transposition was described by Gebert et al. [45], where the femoral head is adjusted and fixed to the proximal osteotomy region with soft tissue or textile implants (Fig. 11.8). Hip transposition provided satisfactory quality of life and functional results, compared with other types of reconstruction [46].

Resection arthroplasty is usually shorter, technically less demanding, and possibly associated with a lower complication rate, compared with complex reconstructive procedures that carry high rates of postoperative complications (Table 11.1). The primary disadvantage of resection arthroplasty is the resulting shortening of the leg, which is not definitively associated with a poor functional outcome [46]. We currently do not usually conduct reconstruction with pelvic prostheses or autograft/allografts for type II resection and largely prefer resection arthroplasty such as pseudoarthrosis or hip transposition. We also believe that a temporal external fixation method is better than long-time bed rest, casting, or the use of a brace to maintain rigid fixation between the femoral head and the remaining pelvis [47, 48].