What are the key considerations and protocols for hip replacement surgery, including preoperative evaluation, implant selection, and postoperative rehabilitation?

Biomechanics of Hip Replacement

Hip replacement biomechanics fundamentally depend on achieving stable fixation through either cemented or uncemented techniques, with implant selection driven by patient age, bone quality, and activity level—hybrid constructs (uncemented acetabular with cemented femoral components) are preferred for elderly patients, while uncemented porous ingrowth designs predominate in young, active populations. 1

Implant Selection Based on Patient Factors

Age and Activity Stratification

• Elderly patients: Hybrid hip replacement (uncemented acetabular component with cemented femoral component) is the widely accepted standard 1
• Young, active patients: Uncemented porous bone ingrowth designs should be used to accommodate higher activity demands and longer expected implant lifespan 1
• Modern implants must withstand substantial demands as patients expect to remain active for extended periods 2

Bone Quality Considerations

• Implant selection must account for bone quality and bone geometry, as these directly influence fixation stability 1
• Poor bone quality may necessitate cemented fixation even in younger patients to ensure adequate mechanical stability 1

Surgical Technique and Biomechanical Principles

Cemented Femoral Component Technique

• Critical communication protocol: The surgeon must verbally announce to the anesthesia team before preparing the femoral canal for cement and prosthesis insertion 3
• Canal preparation sequence: 3
  • Use pressurized lavage system to clean endosteal bone of fat and marrow contents
  • Place distal suction catheter on top of intramedullary plug
  • Insert cement from gun in retrograde fashion on top of plug
  • Remove catheter as soon as blocked with cement
• Avoid excessive pressurization in patients at higher cardiovascular risk, as this can precipitate bone cement implantation syndrome (BCIS) 3

Cardiovascular Risk During Cementation

• Adverse cardiovascular events occur in approximately 20% of cemented hip operations 3
• High-risk patient factors: increasing age, male sex, significant cardiopulmonary disease, and diuretic medication use 3
• The anesthetist must maintain systolic blood pressure within 20% of pre-induction values throughout surgery using vasopressors and/or fluids 3
• Invasive blood pressure monitoring is indicated for higher-risk patients 3

Preoperative Optimization

Prehabilitation Programs

• Preoperative exercise and education should be implemented (Grade A recommendation) to reduce postoperative pain and improve functional outcomes 3
• Preoperative rehabilitation advice reinforced by patient information booklet reduces hospital stay by 3 days and significantly decreases therapy input costs (approximately $810 savings per patient) 4
• Patients receiving preoperative education report higher satisfaction levels (99% vs 80% at 3 months) and develop more realistic surgical expectations 4

Blood Management

• Autologous blood donation combined with collection and infusion of shed blood in the postoperative period greatly minimizes homologous transfusion requirements 1

Postoperative Rehabilitation Protocols

Early Mobilization Strategy

• Immediate full weight-bearing should be used following hip replacement when using modern fixation techniques 5
• Rapid rehabilitation pathway should start immediately after surgery 5
• With comprehensive perioperative protocols, 131 of 150 consecutive patients (87%) were able to walk without assistive devices on the day of surgery 5

Multimodal Pain Management

• Paracetamol plus NSAIDs or COX-2 selective inhibitors represent Grade A first-line therapy 3, 6
• Paracetamol: 1g every 6 hours (maximum 4g daily), used cautiously in liver disease 6
• NSAIDs should be continued regularly for optimal anti-inflammatory effect, not as-needed dosing 6
• Dexamethasone 8-10 mg IV should be administered intraoperatively (Grade A) 3
• Opioids carry Grade D recommendation and should be reserved strictly for rescue analgesia only, never scheduled 3, 6

Regional Anesthesia Considerations

• Single-shot fascia iliaca block or local infiltration analgesia may be considered (Grade D) 3
• If spinal anesthesia is used, intrathecal morphine 0.1 mg could be considered, though this recommendation has significant controversy due to adverse effects (nausea, vomiting, pruritus, delayed ambulation) that conflict with early rehabilitation protocols 3
• Avoid femoral nerve blocks, lumbar plexus blocks, or epidural analgesia due to adverse effects outweighing benefits 6

Prevention of Early Complications

Infection Prevention

• Optimizing the surgical environment, meticulous and efficient surgical technique, and antibiotic prophylaxis remain the cornerstones of infection prevention 1
• All hip fracture surgery should be undertaken or directly supervised by appropriately experienced surgeons and anesthetists on planned trauma lists 3

Heterotopic Ossification Prevention

• Nonsteroidal anti-inflammatory medication and radiation are effective means of preventing heterotopic ossification 1

Venous Thromboembolism Prophylaxis

• For elective hip replacement, LMWH is preferred over adjusted-dose warfarin (INR target 2.5, range 2.0-3.0) as it is more effective in preventing asymptomatic VTE (Grade 1A) 3
• The risk of bleeding at the surgical site may be greater with LMWH than warfarin, requiring individualized selection 3
• Thromboprophylaxis should continue for approximately 5 weeks following total hip replacement, as DVT risk persists for up to 2 months (12-37% incidence without extended prophylaxis) 3

Outcome Assessment

Monitoring Parameters

• Assessment should include patient-reported outcome measures (PROMs) and implant survival rates based on joint replacement registry data 2
• Regular monitoring is essential given high-profile failures of some widely used prostheses (particularly metal-on-metal designs) 2

Postoperative Physical Therapy

• Either formal physical therapy or unsupervised home exercise after total hip arthroplasty is supported by high-quality evidence with moderate strength of recommendation 6
• Early mobilization should be facilitated by optimal multimodal analgesia 6