Файл: NMS Surgery_booksmedicos.org.pdf

Pediatric

Staphylococcus aureus and gram -negative rods predominate as causative organisms in neonates.

Osteomyelitis in young children (i.e., 2–5 years of age) is frequently caused by

Haemophilus species as well as by Staphylococcus and Streptococcus species.

S. aureus is the predominant causal organism in older children (i.e., 5 years or older) and adolescents.

A child with a history of minor trauma who does not improve as would normally be expected must be considered to have possibly developed osteomyelitis.

A child's refusal to bear weight on an extremity demands a workup for osteomyelitis or septic arthritis.

Adults whose immune system is suppressed (e.g., intravenous drug users) and patients with sickle cell disease are predisposed to osteomyelitis from hematogenous spread of unusual organisms.

Patients with immunosuppression and intravenous drug users are susceptible to gram -negative infections, particularly Pseudomonas aeruginosa

In patients with sickle cell anemia , a particularly high incidence of Salmonella osteomyelitis has been observed.

Gonococcal septic arthritis is the most common organism in adolescent, sexually active patients.

Diagnosis. A careful physical examination, complete blood count, sedimentation rate, and bone scan help to confirm the diagnosis. Needle aspiration of the affected bone or joint is the definitive diagnostic test.

Treatment includes appropriate intravenous antibiotics and surgical drainage. Initial antibiotic treatment should be selected to cover the most likely causes of organisms and should always include coverage for Staphylococcus.

Septic arthritis

Etiology

Spontaneous joint infections can occur in children or adults by the hematogenous spread of similar organisms that cause osteomyelitis.

Joint disease , as well as immunosuppression such as occurs in rheumatoid arthritis, can predispose the patient to these joint infections.

Physical examination demonstrates exquisite tenderness, effusion, and severe pain with minimal motion of the joint.

Diagnosis is confirmed by needle aspiration of the joint with synovial fluid analysis demonstrating a markedly elevated white blood cell count with predominance of polymorphonuclear leukocytes.

Synovial fluid white blood cells are greater than 50,000 with more than 90% polymorphonuclear leukocytes. The differential diagnosis includes rheumatoid arthritis and gout. A comparison of the synovial fluid analysis of septic arthritis with other types of arthritides is shown in Table 28 -4.

Treatment includes surgical decompression of the joint (either open or arthroscopic) and appropriate intravenous antibiotic therapy.

Antibiotic therapy should not be instituted before obtaining adequate specimens for a Gram stain, culture, and sensitivity. Penetrating wounds that reach a bone or joint can lead to infection. A common example of this is nail puncture wounds to the sole of the foot. Pseudomonas osteomyelitis has been reported frequently when the nail puncture wound has occurred through an athletic -type shoe.

B Chronic osteomyelitis

Etiology. Chronic osteomyelitis is uncommon; however, it is seen in patients who have had severe open fractures, in immunosuppressed patients, and in patients with pressure ulcerations secondary to paraplegia.

Clinical presentation. Osteomyelitis involving the bony cortex is a particularly difficult problem. Cortical bone has minimal vascularity and is even less well vascularized in the face of osteomyelitis.

P.542

P.543

Therefore, white blood cells, as well as antibiotics, have only limited access to the site of infection.

TABLE 28-4 Examination of the Synovial Fluid

aMay be hemorrhagic

bGroup I or II

SLE, systemic lupus erythematosus; PSS, progressive systemic sclerosis; DM/PM, dermatomyositis/polymyositis.

Reprinted with permission from Rodnan GP, Schumacher HR. Examination of synovial fluid. In: Primer on Rheumatic Diseases, 8th ed. Atlanta: Atlanta Arthritis Foundation; 1983:187.

Early treatment. Attempts to cure chronic osteomyelitis involve the removal of foreign material, including a thorough debridement of infected nonviable bone (sequestrum), open wound care, and a prolonged course of intravenous antibiotics.

Late treatment. After all devascularized bone and soft tissue have been removed, and once a stable wound base has been established, the overlying soft tissue and bone defect need to be addressed.

The bone defect can be packed with antibiotic -impregnated beads (frequently, tobramycin or commercially available gentamicin beads) followed by rotational or free vascularized tissue coverage. Later, the flap can be elevated; the beads can be removed; and massive cancellous autografting can be performed.

Use of a ring external fixator, such as the Ilizarov device , may be used to transport bone to fill defects. Occasionally, the wounds can be left open during transport, and they will close spontaneously once the defect is closed.

Use of vascularized bone grafts , such as the free vascularized fibula or fibular transposition graft, is

an option for large bone defects.

IV Tumors

A Primary bone tumors

Overview

Clinical presentation. The patient with a neoplastic bone lesion presents with pain, swelling, or occasionally, a pathologic fracture induced by minimal trauma. This is true for bony metastases as well as for benign and malignant primary tumors of bone.

Diagnosis. In addition to differentiating a primary tumor from a metastatic lesion of bone, some metabolic processes, such as hyperparathyroidism and infection, must be carefully considered.

Physical examination demonstrates the tumor mass, allowing the selection of appropriate radiographs.

Plain radiographs alone often suggest the etiology and nature of the bone lesion based on its location, appearance, and the response of the surrounding normal bone (Fig. 28 -4).

Malignancy can be expected if the films show:

A large tumor

Aggressive destruction of bone

Ineffective reaction of the bone to the tumor

Extension of the tumor into soft tissue

Benign lesions can be expected if the films show:

A small, well-circumscribed lytic lesion

A thick, sclerotic rim of reactive adjacent bone

No extension into soft tissue

Workup. If there is any question whatsoever that the tumor is malignant, a careful workup must be performed before the biopsy. An incomplete workup or a poorly planned biopsy may prove fatal for the patient or result in loss of limb.

An appropriate workup includes a CT scan and MRI of the involved extremity to stage the tumor and delineate its extent and anatomic relationships. A technetium -99m

(99m Tc) scan is helpful in determining metastatic involvement of distant parts of the skeleton.

If malignancy is suspected, then a CT scan of the chest is important to rule out pulmonary metastases.

A biopsy should be performed only after staging has been completed. The biopsy should be carefully planned so that the biopsy incision can be excised with a definitive surgical resection. The biopsy is best planned and performed by the surgeon who will ultimately

carry out the definitive surgical procedure.

P.544

FIGURE 28-4 Schematic of the distal femur. Numbered sites represent tumor locations: (1) cortical fibrous dysplasia and adamantinoma; (2) osteoid osteoma; (3) chondromyxoid fibroma; (4) osteochondroma; (5) osteosarcoma; (6) chondroblastoma; (7) giant cell tumor; (8) nonossifying fibroma; (9) enchondroma or chondrosarcoma; (10) bone cyst or osteoblastoma; (11) fibrosarcoma or malignant fibrous histiocytoma; (12) fibrous dysplasia; and (13) Ewing's sarcoma or other small round tumors. (Redrawn with permission from

Moser RP, Madewell JE. An approach to primary bone tumors. Radiol Clin North Am. 1987;25[6]:1079–1080.

)

All biopsy incisions should be longitudinal on the limbs.

Biopsy incisions should be made through a muscle belly to avoid contaminating intermuscular planes.

Biopsy incisions should be directed away from neurovascular structures.

Incisions should be directed through structures that can be safely and successfully resected to leave a functional limb if radical excision is later indicated.

Treatment

Surgical treatment continues to be the mainstay of management for both benign and malignant tumors of the extremities. The surgical margin varies significantly with the aggressiveness of the lesion.

Benign tumors can be adequately treated by intralesional or intracapsular excision of the tumor with or without chemical cautery, electrocautery, or cryotherapy and with or without bone grafting of the defect.

Malignant tumors require at least a 2-cm margin.

Metastases. One or two isolated pulmonary metastases of sarcoma (especially osteosarcoma or chondrosarcoma) should be considered for surgical resection, because the literature shows that this occasionally results in a cure and certainly a prolonged life span in these patients.

Adjuvant therapy for malignant tumors

Radiation therapy

Some tumors (e.g., Ewing's tumors) are very sensitive to radiotherapy.

Some protocols include radiation therapy initially, but in general, radiation therapy is not an important part of the protocol.

Chemotherapy , like radiation therapy, may have an important role as adjunctive therapy in anticipation of limb -sparing procedures.

P.545

Ewing's tumors are well known to be very sensitive to various chemotherapeutic regimens.

Osteosarcoma appears to be sensitive to some chemotherapeutic agents, and work is under way to delineate the benefits, because chemotherapy may facilitate limb salvage.

Types of primary bone tumors

Tumors of bone cell origin

Benign osteoid osteoma is a painful lesion that commonly involves the femur or the tibia.

Epidemiology. The tumor occurs in adolescents, and more than 50% of the tumors present in patients aged 10–20 years.

Histology. The lesions are benign and are not prone to malignant degeneration.

Pathologic examination demonstrates a nidus of disorganized, dense, calcified osteoid tissue, which is histologically benign.

Treatment

Typically, aspirin offers excellent relief.

Surgical resection or stereotactical ablation is indicated for lesions that are persistently painful. A bone graft may be necessary.

Osteoblastoma is a benign, rare, painful lesion.

Epidemiology. This lesion occurs most often in the second decade of life and has a predilection for the posterior elements of the spine.

Histology. Osteoblastoma appears very similar to osteoid osteoma; one distinguishing feature is its size. An osteoblastoma is defined as a benign bone-forming lesion greater than 2 cm.

Treatment. Osteoblastomas are cured by surgical excision, if symptoms warrant. Bone grafting may be necessary.

Osteosarcoma

Epidemiology. More than 60% of patients with these tumors are 10–20 years of age.

Clinical presentation

At least 60% of osteosarcomas occur about the knee at either the distal femur or the proximal tibia.

Typically, the patient presents with pain and tumefaction.

Radiographically, the lesion is commonly lytic, but it may be a characteristically blastic lesion of the bone and produce a classic sunburst appearance. An MRI scan and a CT scan show that the lesion is ill-defined with soft tissue extension.

Histology. Histologically, the tumor may be predominantly fibrogenic, chondrogenic, or osteogenic; each of the three cell types predominates in approximately equal numbers of patients. The sine qua non of osteosarcoma is production of malignant osteoid by the tumor stroma.

Treatment

Surgical resection is the cornerstone of management; amputation or limb salvage surgery may be required.

Neoadjuvant chemotherapy (given before surgery) can narrow surgical margins and facilitate limb salvage. A high tumor kill rate observed in the resected specimen correlates favorably with long-term survival.

Adjuvant chemotherapy has a beneficial effect and has increased 5-year survival rates from 10%–20% with surgery alone only to almost 60% with combined