Saddle Prosthesis Research Articles

Reconstructive options in pelvic tumours

Background: Pelvic tumours present a complex problem. It is difficult to choose between limb salvage and hemipelvectomy. Method: Forty three patients of tumours of pelvis underwent limb salvage resection with reconstruction in 32 patients. The majority were chondrosarcomas (20 cases) followed by Ewing sarcoma. Stage II B was the most common stage in malignant lesions and all the seven benign lesions were aggressive (B3). Surgical margins achieved were wide in 31 and marginal in 12 cases. Ilium was involved in 51% of cases and periacetabular involvement was seen in 12 patients. The resections done were mostly of types I & II of Enneking's classification of pelvic resection. Arthrodesis was attempted in 24 patients. Customized Saddle prosthesis was used in seven patients and no reconstruction in 12 patients. Adjuvant chemotherapy was given to all high-grade malignant tumours, combined with radiotherapy in 7 patients. Results: With a mean follow up of 48.5 months and one patient lost to follow up, the recurrence rate among the evaluated cases was 16.6%. Oncologically, 30 patients were continuously disease free with 7 local recurrences and 4 deaths due to disseminated disease and 2 patients died of other causes. During the initial years, satisfactory functional results were achieved with prosthetic replacement. Long-term functional result of 36 patients who were alive at the time of latest follow up was satisfactory in 75% who underwent arthrodesis and in those where no reconstruction was used. We also describe a method of new classification of pelvic resections that clarifies certain shortcomings of the previous systems of classification. Conclusion: Selection of a procedure depends largely on the patient factors, the tumour grade, the resultant defect and the tissue factors. Resection with proper margins gives better functional and oncological results

Treatment of advanced metastatic lesions of the acetabulum using the saddle prosthesis.

Current methods of treating advanced patients with metastatic periacetabular disease are complex and result in high complication rates. The purpose of this study was to show whether the implantation of the saddle prosthesis would serve as an additional tool to help treat metastatic disease in these patients. From 1991 to 2003, 20 patients with advanced metastatic periacetabular lesions (Harrington Class III) were treated using the saddle prosthesis. Goals of surgery were a decrease in pain, functional restoration, and ambulation. The mean age was 61 years. Average length of followup was 20 months. Postoperatively, ambulation was achieved in 16 of 20 patients. There were four postoperative complications (20%) in three patients. Surgical goals were met in 18 of 20 patients. The MSTS-ISOLS emotional score was 2.9 of 5. The average total MSTS-ISOLS score was 16.6 of 30 (55%). Using the Allan scoring system consisting of analgesia, independence and ambulation, and mobility, all scores had significant improvements postoperatively. Careful surgical indications and technique should result in a stable, functional reconstruction allowing patients the ability to ambulate outside the house with a cane. Patients can expect to be emotionally satisfied with the procedure while using nonnarcotic analgesia and can expect an improved quality of life despite bone metastasis.

Complications and functional evaluation of 17 saddle prostheses for resection of periacetabular tumors.

Seventeen saddle prostheses were inserted between 1988 and 1997 after resection of periacetabular tumors. The tumors involved the zones II and III of Enneking classification in 13 patients, the zones I and II in 2 patients, and the zone II in 2 patients. The tumors included 11 chondrosarcomas, 3 Ewing sarcomas, 2 giant cells tumors, and 1 metastasis of renal carcinoma. The tumoral resection was wide "en bloc" in 14 cases, marginal in 2 cases, and intratumoral in 1 case. The mean follow-up period of the patients is 42 months ranging from 8 to 84 months. Local recurrences occurred in five cases and metastases in four cases. Five patients died of tumoral disease and one of intercurrent disease. Complications were observed in 11 cases (65%) including nerve damages (3 cases), deep infections (3 cases), upward migrations of the saddle (4 cases), saddle dislocations (3 cases), sacroiliac subluxations (2 cases), and mechanical failures (2 cases). The modified Musculoskeletal Tumor Society Score (MSTS) and the Toronto Extremity Salvage Score (TESS) were used for functional analysis. Functional results were available for only nine patients of the series with a mean MSTS of 17 points ranging from 11 to 23 points and a mean TESS of 58 points ranging from 39 to 95 points. The saddle prosthesis provided in all cases of this series an early painfree weight-bearing reconstruction with minimal limb shortening, but the functional results remained fair in most patients due to a limited range of motion and a poor abductor strength.

The Saddle prosthesis in periacetabular tumours

The Saddle endoprosthesis provides a means of establishing a stable and mobile articulation between the femur and a partially resected pelvis. Six patients with malignant or aggressive benign bone tumours underwent resection and replacement with custom-made Saddle endoprosthesis. Wide margin was achieved in four cases and marginal margin in two. Follow-up ranged from 24 to 41 months. All the six patients were then alive, five being disease-free. One patient developed deep infection and local recurrence necessitating removal of the prosthesis. The functional results were either excellent or good in five patients.

Megaprosthetic replacement of the pelvis: function in 17 cases.

Between 1980 and 1997, we treated 39 patients (mean age 39 (16-66) years, 24 men) with megaprosthetic replacement of a large bone defect (> 10 cm) of the pelvis. The bone resection was necessary in 38 cases due to malignant bone and soft tissue tumors and in 1 case due to hydatid disease. Polyacetal hemipelvic replacement was performed in 29 cases, CAD hemipelvic replacement in 8 cases, and a saddle prosthesis was inserted in 2 cases. All patients were followed clinically and radiographically. The mean follow-up was 58 (15-110) months. 20 patients have died of their tumor. 10 local infections occurred, in 2 cases necessitating hemipelvectomy. Hip dislocation occurred in 6 cases. 13 of the remaining 17 survivors had good or excellent clinical results according to the Enneking evaluation (MSTS). In 6 of the 17 survivors, radiographs revealed implant loosening.

Revisions of endoprosthetic reconstructions after limb salvage in musculoskeletal oncology.

Of 91 limb-salvage procedures using prosthetic reconstructions because of primary or metastatic bone and soft-tissue tumors 26 revisions were performed in 16 patients. Revision was due to polyethylene wear (9 cases), aseptic loosening (8 cases), recurrent hip dislocation (3 cases), prosthetic stem fracture (2 cases), infection (2 cases), leg length discrepancy (1 case), and traumatic dislocation of a saddle prosthesis (1 case). The follow-up period for tumor control varied from 1.5 to 22 years with a median of 13.5 years. The follow-up period after the last revision operation varied from 0.5 to 12 years with a median of 3 years. At the last follow-up, the functional results had deteriorated compared with after the primary operation in 5 patients and had improved in 2 patients. In the remaining patients, the results did not change.

Malignant pelvic tumors: limb-sparing resection and reconstruction.

Limb salvage of malignant pelvic tumors should be considered when the tumor can be resected with a satisfactory surgical margin or when tumor location is such that amputation would not provide a better margin. Local recurrence rates approximate 17%, with higher recurrence rates in patients with positive microscopic resection margins. Skeletal reconstruction is not necessary following resection of the anterior pelvis or incomplete removal of the ilium because pelvic stability is maintained. In patients with resection of the ilium and loss of pelvic stability, iliosacral arthrodesis provides good function. Reconstruction following periacetabular resections remains extremely challenging. Options include iliofemoral arthrodesis or pseudarthrosis, massive allograft or autoclaved autograft with hip arthroplasty, and pelvic or saddle prosthesis. We favor iliofemoral arthrodesis in the young, active patient because it provides good function with a durable, stable limb.

Limb Salvage in Periacetabular Sarcomas

The oncologic and functional outcome was reviewed in 21 consecutive patients who underwent limb salvaging surgery for periacetabular sarcoma using a new surgical approach and different types of reconstruction between 1972 and 1990. Histologic diagnosis in 86% showed osteosarcomas, chondrosarcomas, and Ewing's tumors. Age ranged from 10.0 to 61.5 years (mean age, 32.9 years). The resection margin was wide in 15 patients but marginal in 2 patients and intralesional in 4 patients. All of the latter patients died of their disease. In all cases where 3-dimensional imaging was used, wide resection margins could be achieved, whereas this was possible only in 50% of the cases with conventional imaging techniques. Seven patients died of their disease 3 to 15 months after surgery, 2 died of chemotherapy induced sepsis, and 2 patients died perioperatively. At followup, 8 patients had no evidence of disease (mean, 57.6 months; range, 12-190 months), and 2 patients were alive with disease. Fourteen patients could be observed for at least 12 months (mean, 41.1 months) and were functionally evaluated according to Enneking's criteria. If extensive resection was necessary, the best results were found if the defect had been reconstructed with a custom made prosthesis. The results were only satisfactory after implantation of saddle prostheses and poor with allografts or when no reconstruction of the bone defect was done.

Reconstruction Using the Saddle Prosthesis Following Excision of Primary and Metastatic Periacetabular Tumors

From 1988 to 1991, 17 patients with malignant periacetabular tumors underwent limb-sparing surgery and reconstruction using the saddle prosthesis. There were 8 patients with primary malignant lesions (Group 1), and 9 patients with metastatic or systemic tumor involving the periacetabular pelvis (Group 2). All resections included excision of the acetabulum. Patients ranged in age from 24 to 76 years (average, 59.8 years). Local control was achieved in all patients. Wide margins were obtained in all patients with primary pelvic tumors. Functional outcomes were rated as follows excellent (10), good (2), fair (1), and poor (4). Three patients, all of whom had pulmonary metastasis before surgery, died within 8 months of surgery. Of the remaining 14 patients, 5 patients died between 6 and 28 months after the index procedure. At the end of the followup period, 9 patients were still alive (6 in Group 1 and 3 in Group 2), with a followup period ranging from 15 to 62 months (average, 33.4 months). The overall results for surviving patients were 7 excellent and 2 good results, with no fair or poor results.

The saddle prosthesis for salvage of the destroyed acetabulum

We report the 12 to 74 month results of our mark I saddle prosthesis after its use as a salvage device for gross loss of pelvic bone stock in 76 patients with failed hip arthroplasties. The implant transmits load between iliac bone and bare polish chrome-cobalt. Our clinical and radiological results indicate that a useful and stable articulation can be achieved in most cases, provided that continued deep infection can be avoided. The appearance of radiological sclerosis at the bearing site in successful cases seems to indicate that significant late migration will not occur. Based on our experience with the mark I prosthesis we have designed and developed a mark II model which has freedom of axial rotation of the saddle. Our early results in 40 cases show a significant improvement over the results which could have been predicted for the mark I device.

Adjustable prosthesis for pulmonary artery banding. Comparison with umbilical tape and teflon bands.

An adjustable, stainless-steel "ball and saddle" prosthesis has been devised for banding the main pulmonary artery in dogs. Comparisons were made between this prosthesis and circumferential cotton umbilical and Teflon tape banding in 20 dogs. The vessel lumen and pressure gradient across the banded area returned to normal after release of the ball and saddle band, but not after release of the circumferential tape bands. However, microscopic damage to the banded artery was noted in all dogs, with attenuation of the media being most evident in dogs with the steel ball and saddle prosthesis.