Читать книгу Synopsis of Orthopaedic Trauma Management - Brian H. Mullis - Страница 92

The principle goal is balancing quality of life and function with disease management. There is little role for restricted weight-bearing or prolonged recovery in the treatment of metastatic disease as median survivorship is often less than 12 months depending on tumor subtype. A sound understanding of disease stage, performance status, patient goals, tumor subtype, and anatomic location are paramount in successful management of these challenging situations.

A. Humerus

1. Location in the bone often guides treatment options, as lesions proximally involving the humeral head or distally about the elbow are likely best managed with prosthetic replacement.

2. Reverse total shoulder and alloprosthetic composite have gained favor in their ability to provide pain relief and return to function while balancing complications (▶Fig. 11.4).

3. Diaphyseal lesions are largely treated with intramedullary fixation or, in rare situations, an intercalary resection and reconstruction (renal cell).

4. Metaphyseal lesions can be approached with internal fixation in the form of plates/screws or an intramedullary nail depending on location and extent of disease. Surgical adjuvants (▶Table 11.3) play an important role in decreasing local tumor burden, limiting progression of disease, and increasing construct stability which can lead to longer implant survivorship.

B. Acetabulum

1. The acetabulum is one of the most challenging anatomic locations in the treatment of bone neoplasms given critical locoregional anatomy and associated surgical morbidity.

2. Complications such as instability, infection, and construct failure have to be weighed against tumor subtype, disease burden, and life expectancy.

3. Nonoperative adjuvants such as radiation or bisphosphonate treatments or minimally invasive options such as interventional cryoablation, radiofrequency ablation, or cementoplasty play important roles in the options available to manage impending fractures.

4. Completed fractures that involve the weight-bearing dome that are associated with debilitating pain and functional limitation are best approached with complex arthroplasty. Use of bone cement and Steinmann pins, porous metal augments, or large acetabular shells combined with antiprotrusio cages can be used to reconstruct large osseous defects.

5. Tumor subtype and extent of disease will often dictate surgical timing as the treatment of periacetabular myeloma and lymphoma will largely be initiated with radiation, bisphosphonates, and chemotherapy followed by delayed surgical reconstruction (▶Fig. 11.5).

C. Femur

1. Pathologic fractures of the femoral head and neck are best served with arthroplasty.

a. Various lengths of stem options (curved and straight) and proximal bodies should be available (calcar replacing, modular).

Fig. 11.4 Lateral radiograph of a humerus demonstrating a long stem cemented modular reverse proximal humerus replacement for reconstruction after en bloc resection of a solitary proximal humerus renal cell pathologic fracture.

Fig. 11.5 Anteroposterior pelvis radiograph demonstrating multiple screws, cement, and a trabecular metal revision acetabular shell used to reconstruct a solitary plasmacytoma with associated pathologic fracture after neoadjuvant external beam radiation and initiation of systemic bisphosphonates.

b. Cement is often advocated in the setting of metastatic disease as fixation does not rely on ingrowth and many patients will go on to receive adjuvant radiation.

c. Caution should be used as intraoperative cardiopulmonary events have been reported with this technique.

d. Low-viscosity cement, forgoing canal pressurization, and the use of cement restrictor as well as high fractions of inspired oxygen and/or a distal vent hole (i.e., 2.5-mm drill bit) can be various strategies employed to lower this risk.

2. The peritrochanteric area of the femur has received the most attention, given the mechanical stress and construct failure observed with both extramedullary and intramedullary devices.

a. Extramedullary devices (plates) are associated with higher failure rates.

b. A statically locked long cephalomedullary device allows immediate weight-bearing through its load sharing properties.

3. A high number of pathologic fractures will never obtain osseous union and therefore several technical considerations are important to consider as the mechanical properties and elastic modulus of the implants vary between traumatic and pathologic etiologies.

a. Proximal nail diameter varies by manufacturer and using a larger-diameter (both proximally and distally) implant increases the bending rigidity of a cannulated implant by the radius to the third power.

b. As a general principle, statically locked (often with more than one distal interlocking screw) antegrade intramedullary nails are recommended for diaphyseal lesions.

c. Retrograde femoral nails should be avoided as they do not protect the femoral neck and risk intra-articular contamination and progression of disease.

d. Implants with a lower radius of curvature (more bowed) can facilitate more distal fixation when performing antegrade fixation for quite distal fractures (i.e., extreme nailing).

e. A dynamic interlocking hole can be used for “kissing screws” with both medial and lateral directed interlocking screws.

f. Hybrid fixation with plate/nail can provide accurate and reliable spanning fixation and allow for immediate weight-bearing.

g. The use of blocking screws to increase construct stability (▶Fig. 11.6).

Fig. 11.6 A statically locked long antegrade intramedullary femoral nail with low radius of curvature allowing more distal placement for this metaphyseal metastatic lung carcinoma pathologic fracture. Note “kissing screws” through dynamic interlocking hole, blocking screw and plate augmentation to allow immediate weight-bearing and increase construct rigidity with relatively short working length.

4. Arthroplasty removes many of the limitations of internal fixation by replacing the diseased and fractured bone, but benefits must be balanced with risk.

5. Wound healing, infection, and instability remain challenges in the often nutritionally and immunocompromised hosts.

6. Disease stage, performance status, patient goals, and the plan for adjuvant treatments (timing of chemotherapy) need to be carefully considered when deciding between arthroplasty and internal fixation.

D. Tibia

1. Pathologic fractures of the tibia are less frequently encountered, but can provide unique management challenges.

2. En block resection/proximal tibia replacement presents functional challenges with extensor mechanism reconstruction and therefore the use of surgical adjuvants in addition to robust fixation and poly (methyl methacrylate) (PMMA) can often provide durable fixation while providing patients an early functional return with limited restrictions (▶Fig. 11.7).

3. Intramedullary nail tenets as outlined for the femur have similar application to impending or completed pathologic fractures of the tibia.

a. Large-diameter nails.

b. Numerus interlocking screws in multiple planes of fixation.

c. Adjuvant blocking screws to increase short working length stability (▶Fig. 11.6).

d. Extra-articular insertion technique.

e. Meticulous respect for soft tissues.

Fig. 11.7 Postoperative anteroposterior radiograph of a proximal tibia metastatic renal cell fracture treated with adjuvants including embolization, open curettage, argon beam thermal coagulation, cementation and internal fixation to allow minimal postoperative restrictions and initiate systemic chemotherapy in a timely fashion while preserving the extensor mechanism of the knee.