Metastatic Disease to Acetabulum

Courtesy:
Alexander Christ MD,Assistant Professor, UCLA, Los Angeles

Overview of the Webinar

• Educational session focusing on surgical and non?surgical management of metastatic disease affecting the acetabulum.
• Discussion centered on evolving treatment strategies, reconstruction techniques, and multidisciplinary care for patients with metastatic bone disease.

Background of the Presenter

• Orthopedic oncologist specializing in tumors and tumor?related conditions of the musculoskeletal system.
• Clinical focus includes limb salvage surgery and reconstructive techniques following tumor removal.
• Training background includes advanced study in molecular biophysics and biochemistry followed by medical education and specialized orthopedic oncology training.
• Research interests include sarcoma biology, drug delivery methods, and innovative reconstruction techniques after tumor surgery.

Early Understanding of Acetabular Metastatic Disease

• One of the earliest widely referenced clinical experiences described treatment of patients with metastatic acetabular lesions.
• Median survival after the first pathological fracture was approximately 18–19 months.
• Patients with breast cancer metastasis demonstrated relatively longer survival compared with other malignancies.
• Survival in patients with lung cancer metastasis was significantly shorter.
• Radiation therapy was routinely used as part of treatment in early studies.

Classification of Acetabular Metastatic Defects

• Class 1: Minimal metastatic involvement with largely intact acetabulum.
• Class 2: Defect involving the medial wall of the acetabulum.
• Class 3: Extensive structural destruction including lateral cortex or posterior wall.
• Class 4: Isolated metastatic lesion potentially amenable to wide surgical resection.

Traditional Surgical Treatment Strategies

• Class 1 lesions commonly treated with cemented total hip arthroplasty.
• Class 2 lesions treated using cemented total hip arthroplasty combined with reinforcement devices such as anti?protrusio rings.
• Class 3 lesions required extensive tumor removal, mechanical reinforcement using pins or screws, and hip reconstruction with cemented arthroplasty.
• Class 4 lesions sometimes treated with wide resection in selected solitary metastases.

Historical Outcomes

• Significant reduction in pain following surgery.
• Many patients regained the ability to walk with or without assistive devices.
• Early surgical techniques used relatively simple implants and instrumentation compared with modern technology.

Changing Epidemiology of Bone Metastases

• Bone is a frequent site of metastasis in many cancers.
• Breast and prostate cancers frequently metastasize to bone, with rates reported up to 70 percent in post?mortem studies.
• Approximately 40 percent of common carcinomas eventually produce symptomatic bone metastases.
• Large population studies suggest hundreds of thousands of patients are affected annually in the United States.
• The pelvis is the third most common site for bone metastases after the spine and femur.

Recent Data on Tumor Types Causing Bone Metastasis

• Lung cancer represents the most common source of metastatic bone disease in contemporary datasets.
• Prostate and breast cancers remain major contributors.
• Gastrointestinal malignancies are increasingly recognized as significant sources of bone metastasis.
• Patterns of metastatic disease continue to evolve as patients live longer with cancer.

Impact of Improved Cancer Therapies

• Advances such as targeted therapy and immunotherapy have significantly improved survival in several cancers.
• Patients with metastatic disease are living longer than previously expected.
• Orthopedic reconstructions must therefore be more durable to accommodate increased life expectancy.

Tools for Survival Prediction

• Clinical prediction tools can estimate survival after pathological fracture.
• These tools incorporate patient factors, tumor characteristics, and treatment variables.
• Such predictions help guide the selection of surgical procedures with appropriate durability.

Advances in Surgical Technology

• Modern implants include porous metal surfaces designed for bone ingrowth.
• Fenestrated and cannulated screws allow improved fixation and cement augmentation.
• Dual mobility hip implants help reduce dislocation risk.
• Computer navigation and advanced imaging techniques assist with accurate implant placement.

Principles of Multidisciplinary Care

• Management requires collaboration between orthopedic surgeons, medical oncologists, radiation oncologists, and primary care providers.
• Patient nutritional and metabolic status must be optimized before surgery.
• Radiation therapy often serves as a first?line treatment for bone metastases.
• Systemic cancer therapy is critical for controlling overall disease progression.
• Medications such as bisphosphonates help reduce skeletal complications.

Goals of Surgical Treatment

• Relief of pain caused by bone destruction or fracture.
• Immediate structural stability of the hip and pelvis.
• Durable fixation that allows early weight?bearing.
• Restoration of walking ability and daily function.
• Minimization of complications that could delay cancer therapy.

Challenges with Traditional Reconstruction

• Some surgical techniques have relatively high complication rates.
• Common complications include mechanical failure, infection, and hip dislocation.
• Large surgical exposures increase soft tissue disruption and instability risk.

Strategies to Reduce Complications

• Use of dual mobility hip implants can significantly reduce dislocation rates.
• Constrained liners may also improve joint stability.
• Appropriate use of postoperative radiation therapy improves local disease control.

Use of Porous Metal Implants

• Porous metal acetabular implants can provide durable fixation in selected patients.
• Clinical studies have demonstrated low mechanical failure rates and good long?term stability.
• These implants may be particularly useful for patients expected to survive longer.

Emerging Reconstruction Technologies

• Custom implants created using three?dimensional manufacturing techniques are being developed.
• These implants can be designed to match individual patient anatomy.
• Manufacturing time and regulatory approval processes have historically limited their widespread use.
• Recent improvements are making these implants more accessible.

Minimally Invasive Treatment Options

• Percutaneous cement injection techniques can stabilize bone defects and reduce pain.
• Procedures such as cryoablation or radiofrequency ablation may be combined with cement stabilization.
• These options are useful for patients who cannot tolerate major surgery.

Percutaneous Screw and Cement Techniques

• New approaches use image guidance to place screws around the acetabulum through small incisions.
• Bone cement is injected to reinforce structural stability.
• Many patients can mobilize soon after the procedure.
• Some patients may later undergo standard hip replacement if required.

Current Treatment Decision Framework

• Extent of tumor involvement in the acetabulum.
• Patient overall health and expected survival.
• Potential benefits and risks of surgery.
• Availability of systemic cancer therapies.
• Need for durable versus minimally invasive reconstruction.

Examples of Reconstruction Approaches

• Contained defects may be treated with standard cemented total hip replacement.
• Cavitary or medial wall defects may require reinforcement rings or cages.
• Extensive disease may require multiple screws across the pelvis combined with cemented hip implants.
• In severely ill patients, cement stabilization alone may provide adequate pain relief.

Future Directions

• The number of patients with metastatic bone disease is expected to increase.
• Longer survival will require more durable orthopedic reconstructions.
• Advanced imaging, navigation systems, and robotic technology may improve surgical precision.
• Minimally invasive techniques are likely to expand.

Economic and Ethical Considerations

• Increasing demand for complex reconstruction will raise healthcare costs.
• Decisions regarding resource allocation and treatment value will become increasingly important.
• Evidence demonstrating improved quality of life will help support these interventions.

Importance of Teamwork and Training

• Successful management requires close coordination among specialists.
• Surgeons must stay familiar with new implants and technologies.
• Collaboration with colleagues is essential when performing technically complex procedures.

Key Takeaways

• Metastatic disease of the acetabulum is a complex condition requiring individualized treatment.
• Advances in oncology have extended patient survival, changing surgical decision?making.
• Modern implants and minimally invasive techniques are improving outcomes.
• Multidisciplinary care and appropriate patient selection remain central to successful treatment.