Predators modify the evolutionary response of prey to temperature change.

As climate regimes shift in many ecosystems worldwide, evolution may be a critical process allowing persistence in rapidly changing environments. Organisms regularly interact with other species, yet whether climate-mediated evolution can occur in the context of species interactions is not well understood. We tested whether a species interaction could modify evolutionary responses to temperature. We demonstrate that predation pressure by Dipteran larvae (Chaoborus americanus) modified the evolutionary response of a freshwater crustacean (Daphnia pulex) to its thermal environment over approximately seven generations in laboratory conditions. Daphnia kept at 21°C evolved higher population growth rates than those kept at 18°C, but only in those populations that were also reared with predators. Furthermore, predator-mediated selection resulted in the evolution of elevated Daphnia thermal plasticity. This laboratory natural selection experiment demonstrates that biotic interactions can modify evolutionary adaptation to temperature. Understanding the interplay between multiple selective forces can improve predictions of ecological and evolutionary responses of organisms to rapid environmental change.

Classification of failure of limb salvage after reconstructive surgery for bone tumours : a modified system Including biological and expandable reconstructions.

Previous classification systems of failure of limb salvage focused primarily on endoprosthetic failures and lacked sufficient depth for the effective study of the causes of failure. In order to address these inadequacies, the International Society of Limb Salvage (ISOLS) formed a committee to recommend revisions of the previous systems. The purpose of this study was to report on their recommendations. The modifications were prepared using an earlier, evidence-based model with subclassification based on the existing medical literature. Subclassification for all five primary types of failure of limb salvage following endoprosthetic reconstruction were formulated and a complementary system was derived for the failure of biological reconstruction. An additional classification of failure in paediatric patients was also described. Limb salvage surgery presents a complex array of potential mechanisms of failure, and a complete and precise classification of types of failure is required. Earlier classification systems lacked specificity, and the evidence-based system outlined here is designed to correct these weaknesses and to provide a means of reporting failures of limb salvage in order to allow the interpretation of outcome following reconstructive surgery.

Proximal femoral allograft-prosthesis composites in revision hip replacement: a 12-year follow-up study.

We report the use of an allograft prosthetic composite for reconstruction of the skeletal defect in complex revision total hip replacement for severe proximal femoral bone loss. Between 1986 and 1999, 72 patients (20 men, 52 women) with a mean age of 59.9 years (38 to 78) underwent reconstruction using this technique. At a mean follow-up of 12 years (8 to 20) 57 patients were alive, 14 had died and one was lost to follow-up. Further revision was performed in 19 hips at a mean of 44.5 months (11 to 153) post-operatively. Causes of failure were aseptic loosening in four, allograft resorption in three, allograft nonunion in two, allograft fracture in four, fracture of the stem in one, and deep infection in five. The survivorship of the allograft-prosthesis composite at ten years was 69.0% (95% confidence interval 67.7 to 70.3) with 26 patients remaining at risk. Survivorship was statistically significantly affected by the severity of the pre-operative bone loss (Paprosky type IV; p = 0.019), the number of previous hip revisions exceeding two (p = 0.047), and the length of the allograft used (p = 0.005).

Urological assistance during therapeutic pubectomy.

PURPOSE: A technique is described to optimize exposure during female pubectomy to minimize injury to associated urological structures. MATERIALS AND METHODS: Three females with diagnosed osteomyelitis pubis underwent pubectomy. Before resection of the bone, the patients underwent a formal combined transvaginal and retropubic dissection. This dissection allowed complete freeing of the urethra and bladder from areas of orthopedic resection and optimized surgical exposure. RESULTS: All operations were completed successfully with no incidence of intraoperative urological structure injury and no postoperative pelvic instability. None of the patients required intraoperative or postoperative blood transfusions. Pelvic pain resolved in all 3 patients. CONCLUSIONS: Using a combined transvaginal and retropubic technique, the urologist may assist the orthopedic surgeon at the time of pubectomy. This technique potentially minimizes the incidence of vesical and urethral injury.

Bone tumors of the coracoid process of the scapula.

Bone tumors of the coracoid process of the scapula are rare, and diagnosis and treatment often are delayed. The records of 18 patients with bone tumors of the coracoid process were reviewed. Histologic types included eight cases of ordinary chondrosarcoma, three cases of dedifferentiated chondrosarcoma, two cases of osteoid osteoma, and one case each of osteosarcoma, plasmacytoma, lymphoma, giant cell tumor, and aneurysmal bone cyst. All 18 patients had shoulder pain, and eight of them had been treated with steroid injections for nonneoplastic conditions. Radiologically, chondrosarcoma did not always show clear cortical destruction, and one giant cell tumor had features mimicking those of chondrosarcoma. Five patients (three with dedifferentiated chondrosarcoma, one with chondrosarcoma, one with plasmacytoma) died of disease. The coracoid process was the site with a markedly high proportion of chondrosarcomas. Bone tumors of the coracoid process may be difficult to detect on plain radiographs. In the patient with persistent shoulder pain unresponsive to the selected treatment, additional imaging studies should be considered to eliminate the possibility of a bone lesion.

Functional laboratory assessment after oncologic shoulder joint resections.

A laboratory evaluation was undertaken to assess the shoulder range of motion and distal strength after oncologic resection and reconstruction involving the shoulder joint and to compare these functional parameters based on potentially important variables. Inclusion in the study was limited to 32 patients with bone tumors of the proximal humerus or scapula treated surgically by resection of the shoulder joint including the proximal humerus from 1976 through 1992. Active shoulder range of motion and isometric elbow extension and forearm supination strength are significantly less after surgery in patients with greater amounts of bony resection and with resection of the deltoid. Patients who had a modified Tikhoff-Linberg resection were able to achieve 10 degrees to 15 degrees greater shoulder motion in each direction than were patients who had the classic procedure including complete scapulectomy. However, elbow flexion and extension strength and forearm pronation strength were greater for the patients with the classic resection. Osteoarticular allografts as a reconstructive alternative provide as a group the best shoulder motion and overall distal upper extremity strength, but these reconstructions were performed only when the rotator cuff muscles and deltoid were able to be reconstructed. Diminishing elbow strength was seen with longer followup in the patients with osteoarticular reconstructions, corresponding temporally to subchondral collapse observed on radiographs. Range of shoulder motion except rotation was just as good for allograft vascularized fibular arthrodeses as for the osteoarticular allografts, but strength was significantly less with the arthrodeses.

Distal upper extremity function following proximal humeral resection and reconstruction for tumors: contralateral comparison.

BACKGROUND: Most functional analyses after limb salvage operations about the shoulder have focused on proximal function with the assumption that distal function is largely unaffected. This analysis examines distal function objectively. METHODS: Objective laboratory data regarding distal upper extremity strength after reconstructive procedures for tumors near the shoulder joint was collected over a 16-year period. Thirty-two patients were able to participate fully in the data collection at an average most recent follow-up duration of > 3.5 years. RESULTS: Statistically significant reductions on the involved side compared with the uninvolved side in grip, forearm pronation, forearm supination, elbow flexion, and elbow extension strength were documented (p < 0.05). The magnitude of reduction in strength diminishes distally, with the greatest effect in this group of patients being observed in elbow extension, followed by elbow flexion, forearm supination, and forearm pronation. Grip strength consistently showed the least amount of strength reduction compared with the uninvolved side, even within resection and reconstruction groups. Subjective patient rating of dexterity was no less than 3 of 5. Ninety percent of patients rated their dexterity 4 of 5 (52%) or 5 of 5 (38%). CONCLUSIONS: Despite the insistence of "normal" function in the distal upper extremity after limb salvage procedures, complete normality is not maintained. However, the degree of maintenance of distal function appears to be high, especially for grip strength and forearm pronation strength, and patient satisfaction is acceptable.

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 for neoplasms of the shoulder girdle. Intermediate reconstructive and functional results.

The intermediate functional results were assessed for fifty-seven patients who had had a limb-salvage procedure for treatment of a tumor of the shoulder girdle region at our institution from 1980 through 1990. Fifty-three patients had a malignant bone tumor (a sarcoma) and four had an extensive giant-cell tumor. The resections were classified according to the system of the Musculoskeletal Tumor Society. A variety of reconstructive procedures were performed after resection of the tumor, with the choice of procedure depending on the type of resection and the needs of the patient. The functional results were described and graded quantitatively according to the functional rating system of the Musculoskeletal Tumor Society. The average duration of follow-up was 5.3 years (median, 4.6 years) for the forty-seven patients who were still alive at the time of the latest follow-up examination. Eight patients died of disease and two others died of unrelated malignant tumors an average of 1.8 years postoperatively. The resection of the tumor was classified as wide in forty of the fifty-three patients who had a sarcoma and as marginal in thirteen; four patients had local recurrence (two, after a wide resection, and two, after a marginal resection). One of the four patients who had a giant-cell tumor had local recurrence. The functional results were related to the type of resection and the method of skeletal reconstruction. After resection of the entire scapula and the proximal aspect of the humerus, reconstruction with a spacer frequently resulted in asymptomatic superior subluxation of the implant and poor function of the shoulder. After extra-articular resection of the glenoid cavity and the proximal aspect of the humerus with loss of the abductor mechanism, osseous arthrodesis resulted in good function that was superior to that found after reconstruction with a spacer or a proximal humeral replacement prosthesis. Our preferred method to achieve fusion was insertion of an intercalary allograft and a vascularized fibular graft. However, the allograft fractured in three of four patients in whom primary fusion had been obtained with this technique. An osteoarticular allograft inserted after intra-articular resection of the proximal aspect of the humerus and preservation of the abductor mechanism provided good function that was superior to that found after reconstruction with a proximal humeral replacement prosthesis, which produced symptomatic instability that led to a secondary arthrodesis in some patients. However, subchondral fracture and collapse of the osteoarticular allograft occurred in four of eight patients by the time of the latest follow-up examination. The results of all methods of reconstruction were satisfactory with regard to pain, emotional acceptance, and manual dexterity. We believe that the use of a method of reconstruction that is appropriate with regard to the needs of the patient and preoperative counseling regarding the expected functional level and restrictions of activity are critical for a high level of postoperative satisfaction.

Ewing's sarcoma of the proximal femur.

The cases of 16 patients with Ewing's sarcoma of the proximal femur treated in the era of multiagent chemotherapy were reviewed, with emphasis on the mechanical problem of tumor involvement in this structurally demanding site. Fourteen patients received chemotherapy and local radiotherapy as the initial primary treatment. One patient had chemotherapy and radiotherapy, followed by wide local resection. One patient had amputation, followed by chemotherapy, for pathologic fracture and extensive soft tissue involvement at presentation. Two local recurrences occurred. Excluding the 2 patients whose femurs were fixed prophylactically, the pathologic fracture rate was 79%. In addition, by excluding the 2 patients who died before fracture, the pathologic fracture rate was 92%. Nonunion occurred in 5 (71%) of the 7 pathologic fractures not treated by resection and required as many as 5 additional surgical procedures to obtain union. At latest followup evaluation (average, 6.3 years), 10 patients had no evidence of disease, 1 was alive with disease, and 5 had died of their disease. Options for management should include primary resection and reconstruction or prophylactic internal fixation after completion of chemotherapy plus or minus radiotherapy.

Osteomyelitis secondary to an osteoenteric fistula.

Osteomyelitis involving the symphysis pubis is a rare complication of pelvic surgery, and differentiation with osteitis pubis may be difficult. Herein we present a case of a patient in whom a disabling public pain developed 4 months after a radical cystectomy for bladder cancer. His pain was unresponsive to medical and antibiotic therapy and subsequently proved to be caused by public osteomyelitis secondary to a small-bowel fistula precipitated by cancer recurrence.

Osteoblastoma: clinicopathologic study of 306 cases.

The clinical, radiologic, and pathologic features of 306 osteoblastomas were analyzed. Seventy-five were Mayo Clinic cases and 231 were from consultation files. Males outnumbered females two to one. The age range was 6 months to 75 years (mean age, 20.4 years). The vertebral column including the sacrum was the most frequent site (32%). Pain was the usual complaint and neurologic findings were associated with vertebral tumors. Although most tumors were well circumscribed, cortical expansion and destruction were common radiographic findings (39%), and 12% had features suggestive of malignancy. Large, epithelioid osteoblasts were seen in 24% and were the predominant cellular element in 10%. A distinctive epithelioid multifocal pattern was recognized. Recurrence rates were 16% (Mayo Clinic cases) and 21% (consultation cases). Tumors involving the central neuraxis were associated with greater morbidity and mortality. Aggressive behavior is within the biologic spectrum of osteoblastomas, and histopathology alone does not appear to be a reliable predictor of aggressiveness. The most important differential diagnosis is osteosarcoma.

[Resection of pelvic sarcomas. Reconstruction techniques without use of endoprostheses]. / Resektion von Beckensarkomen. Wiederherstellungstechniken ohne Verwendung von Endoprothesen.

Advances in preoperative imaging techniques and surgical expertise now permit limb sparing resections of pelvic sarcomas to be performed in appropriate patients with an acceptable risk of local recurrence. Reconstruction of the skeletal defect remains, however, problematic. Many techniques have been employed, all with advantages and disadvantages. Arthrodesis for the unstable pelvis has been our preferred reconstructive procedure. When successful, we find this a durable and pain-free reconstruction for the young, active patient.

Integration of limb-sparing surgery, brachytherapy, and external-beam irradiation in the treatment of soft-tissue sarcomas.

Advances in the integration of limb-sparing surgery and adjuvant radiation therapy have nearly eliminated the need for ablative or radical resections in the management of soft-tissue sarcomas. The combination of wide or marginal surgical resections, brachytherapy, and external-beam irradiation resulted in a local recurrence rate of 9% in 68 patients followed for a minimum of two years. All recurrences were in nonsubcutaneous high-grade lesions. Treatment-related morbidity occurred in 22% of patients. Wound-healing complications developed in 17% and resolved with nonoperative treatment in half. These results support the efficacy of limb-sparing surgery and adjuvant radiation therapy in the management of soft-tissue sarcomas. Integration of chemotherapy may be necessary for the higher-grade lesions, although effectiveness is uncertain.

Metastatic disease of the spine.

Advances in imaging studies and techniques of spinal stabilization permit improved surgical treatment of patients with metastatic disease of the spine. Preoperative evaluation, selection of patients for operative management, and results of published clinical series are reviewed. Surgical approaches for optimal tumor excision, neural decompression, and spinal stabilization are discussed.

Ewing's sarcoma. Prognostic factors, disease control, and the reemerging role of surgical treatment.

Advances in the treatment of Ewing's sarcoma have been dramatic. Present treatment protocols control local disease by radiotherapy, surgery, or both; systemic spread is limited by aggressive multiagent chemotherapy. In patients with localized osseous Ewing's sarcoma, five-year survival rates now range from 54% to an estimated 74%. With late relapse not uncommon, control of the primary lesion is critical to long-term survival. Several studies now show improved local control and possibly improved survival of patients with surgical treatment of primary osseous Ewing's sarcoma.

Salvage of the limb in the treatment of malignant pelvic tumors.

From 1970 through 1985, at the Mayo Clinic, sixty patients had operative treatment, with salvage of the limb, for a primary malignant tumor of the pelvis. Chondrosarcoma, osteosarcoma, and fibrosarcoma were common diagnoses. There were twenty-three iliosacral, twenty-five acetabular, and twelve ischiopubic lesions. Most of the resections were done with a wide margin and disruption of femorosacral continuity. Reconstruction included ten iliosacral, fourteen iliofemoral, and three ischiofemoral arthrodeses, and approximately 50 per cent of the procedures resulted in fusion. The average length of follow-up exceeded five years. Seventeen per cent of the patients, primarily those in whom an iliosacral lesion extended into the sacrum or along the spinal column, had a local recurrence. Twenty-one patients (37 per cent) had metastasis. The best functional results were seen after resections in which femorosacral continuity was maintained or reconstructed. If satisfactory margins can be achieved by the excision of a pelvic tumor, salvage of the limb is justified from both an oncological and a functional standpoint.