3D Printing in Hip Preservation Surgery

Courtesy: Dr. V Salil Upasani, Dr Ashok Shyam, Ortho TV

 

3D Printing in Complex Hip Preservation

Overview

• Three-dimensional printing is emerging as a useful adjunct in orthopaedic surgery, particularly for complex hip deformities and hip preservation procedures.
• Its greatest value is as a complementary technology that supports, rather than replaces, clinical judgment, surgical expertise, and conventional imaging.
• Patient-specific three-dimensional models can be used for:
  • Preoperative planning.
  • Understanding complex three-dimensional deformities.
  • Surgical simulation.
  • Patient and family education.
  • Resident and fellow training.
  • Orthopaedic research.
  • Development and testing of patient-specific implants and instruments.

Applications in Orthopaedic Surgery

• Three-dimensional printing has been investigated for several challenging orthopaedic procedures.
• Reported applications include:
  • Planning correction of congenital spinal deformities.
  • Surgical planning for complex pelvic bone tumors.
  • Patient-specific distal radius osteotomy planning.
  • Complex proximal femoral reconstruction.
  • Pediatric pelvic osteotomy planning.
  • Simulation and training for technically demanding procedures.

Patient-Specific Models for Surgical Planning

• A three-dimensional model can convert conventional computed tomography data into a physical representation of the patient’s anatomy.
• This allows the surgeon to:
  • Directly visualize deformity from multiple perspectives.
  • Identify the location and extent of abnormal bone morphology.
  • Simulate different osteotomy options.
  • Determine the likely amount and direction of correction.
  • Assess implant positioning before surgery.
  • Anticipate technical difficulties during the procedure.
• A mock operation performed on the printed model can provide a practical rehearsal before undertaking the actual operation.

Application in Slipped Capital Femoral Epiphysis

• Slipped capital femoral epiphysis produces a complex three-dimensional deformity of the proximal femur.
• Severe deformity may require a corrective proximal femoral osteotomy.
• Three-dimensional models can assist in understanding the individual components of the deformity and planning the desired correction.

Three-Plane Proximal Femoral Osteotomy

• A three-plane corrective osteotomy can address the deformity through controlled correction in multiple planes.
• Patient-specific models can be used before surgery to:
  • Determine the osteotomy configuration.
  • Simulate the correction.
  • Estimate the amount of bone resection.
  • Plan implant placement.
  • Anticipate the final alignment.

Reported Benefits

• In a single-institution clinical study, patients treated using three-dimensional models were compared with patients treated without models and with a historical cohort.
• The use of patient-specific models was associated with:
  • Reduced operative time.
  • Reduced fluoroscopy exposure.
  • Comparable radiographic correction.
• There was no significant difference in blood loss.
• The important finding was not necessarily that three-dimensional planning produced a superior final correction, but that similar correction could be achieved more efficiently.
• The study also reported fewer implant-related technical problems in the model-assisted group.

Limitations

• The findings should be interpreted cautiously because:
  • The sample size was small.
  • The study was not a prospective randomized comparison.
  • The groups had different characteristics.
  • Follow-up was not uniform.
• Larger prospective studies are required before definitive conclusions can be drawn regarding the clinical superiority of three-dimensional printing.

Three-Dimensional Planning of Pediatric Pelvic Osteotomies

• Acetabular dysplasia requires individualized correction because the pattern of acetabular deficiency varies between patients.
• Common pelvic osteotomies used in children include:
  • Dega osteotomy.
  • Pemberton osteotomy.
  • San Diego osteotomy.
• Although these procedures may appear similar externally, their osteotomy paths and mechanisms of correction differ substantially.

Understanding the Osteotomy Geometry

• Three-dimensional printed pelvic models allow the surgeon to appreciate the internal anatomy and the relationship between:
  • The osteotomy.
  • The acetabulum.
  • The triradiate cartilage.
  • The medial wall of the ilium.
  • The posterior pelvic structures.
• The different osteotomies produce different patterns of acetabular reorientation and coverage.

Simulation Using Identical Patient-Specific Pelvic Models

• A particularly useful research approach is to produce multiple models of the same patient’s pelvis.
• Different osteotomies can then be performed on separate copies of the model.
• Three-dimensional computed tomography analysis can subsequently be used to compare the resulting changes in acetabular coverage.

Principal Findings

• Different pelvic osteotomies produce different patterns of acetabular coverage.
• In the reported experimental analysis:
  • Pemberton and Dega osteotomies produced greater anterior coverage.
  • San Diego osteotomy produced relatively greater posterior coverage.
• This supports the principle that pelvic osteotomy should be selected according to the individual pattern of acetabular deficiency, rather than applying a single technique uniformly to every patient.
• The models also demonstrated a reduction in acetabular volume following correction.
• The reduction in volume was broadly comparable among the osteotomy techniques evaluated.

Complex Proximal Femoral Reconstruction After Infection

• Three-dimensional printing can be particularly valuable when conventional imaging makes it difficult to appreciate the complete extent of a deformity.
• An example involved a young child with:
  • Septic arthritis of the hip.
  • Femoral osteomyelitis.
  • Extensive surrounding muscle inflammation.
  • Methicillin-resistant Staphylococcus aureus infection.
• The infection required repeated surgical debridement and prolonged antimicrobial treatment.
• Following control of the infection, the child developed:
  • A pathological fracture.
  • Extensive destruction of the femoral canal.
  • Malunion.
  • Proximal femoral deformity.
  • Varus deformity at the femoral head-neck region.
  • Rotational deformity.
  • Associated shaft deformity.

Role of Three-Dimensional Printing

• A patient-specific three-dimensional model of the pelvis and both proximal femora was produced.
• The model enabled detailed assessment of:
  • The residual deformity.
  • The relationship between the femoral head, neck, and shaft.
  • Possible osteotomy sites.
  • The feasibility of reconstruction.
• Implant selection and modification could also be tested on the model before surgery.
• A small plate was customized to fit the patient’s unusually small and deformed proximal femur.
• After appropriate sterilization and surgical preparation, the customized implant was used during reconstruction.
• Follow-up demonstrated substantial improvement in proximal femoral alignment and biomechanics after reconstruction and subsequent implant removal.

Complex Residual Perthes-Type Proximal Femoral Deformity

• Another application involved an adolescent with a complex proximal femoral deformity following previous hip disease consistent with residual Perthes-type deformity.
• Three-dimensional computed tomography demonstrated abnormalities that were difficult to appreciate fully on conventional two-dimensional radiographs.

Surgical Options Considered

• Several reconstructive procedures were evaluated on the patient-specific model, including:
  • Valgus femoral osteotomy.
  • Femoral neck lengthening procedures.
  • Intertrochanteric osteotomy.
  • Surgical dislocation with femoral head reduction osteotomy.
• Performing these procedures on a physical model allowed direct comparison of the expected anatomical correction.

Patient-Specific Surgical Selection

• After simulation, a multi-part proximal femoral corrective osteotomy was selected.
• Postoperative imaging demonstrated substantial improvement in:
  • Proximal femoral morphology.
  • Mechanical alignment.
  • Hip biomechanics.
• Serial follow-up showed maintenance of the correction after healing and subsequent implant removal.

Advantages of Three-Dimensional Printing

• Improved anatomical understanding
  • Provides a tangible representation of complex deformity.
  • Allows visualization of anatomy from multiple angles.
• Better preoperative planning
  • Helps determine osteotomy location and orientation.
  • Allows simulation of correction before surgery.
  • Facilitates implant planning.
• Surgical rehearsal
  • Complex procedures can be practiced before entering the operating room.
  • Potential technical problems can be identified in advance.
• Potential reduction in operative time
  • Preoperative simulation may improve surgical efficiency.
• Reduced radiation exposure
  • Better preoperative planning may reduce dependence on intraoperative fluoroscopy in selected procedures.
• Education and training
  • Provides residents and fellows with realistic models for practicing complex procedures.
  • Allows repeated simulation without exposing patients to operative risk.
• Patient and family communication
  • Physical models can make complex deformities easier for patients and families to understand.
• Research
  • Identical patient-specific models can be used to compare different surgical techniques under controlled conditions.
• Patient-specific implants
  • Customized implants or guides can potentially be designed for unusual anatomy.

Practical Considerations

• Three-dimensional printing does not replace:
  • Clinical examination.
  • Conventional radiography.
  • Computed tomography.
  • Magnetic resonance imaging when indicated.
  • Sound surgical judgment.
• Its value depends on accurate imaging data, appropriate segmentation, reliable model production, and careful surgical interpretation.
• The technology is particularly useful when the deformity is:
  • Complex.
  • Three-dimensional.
  • Unusual.
  • Difficult to understand using conventional imaging alone.

Cost and Accessibility

• Desktop three-dimensional printers can provide a relatively accessible option for producing anatomical models.
• The cost of the printer may be modest compared with many advanced medical technologies, while the material cost of an individual model can be relatively low.
• Actual clinical implementation also requires consideration of:
  • Imaging and segmentation software.
  • Personnel and technical expertise.
  • Model production time.
  • Sterilization requirements when models or customized implants are taken into the operating room.
  • Regulatory and quality-control requirements for patient-specific implants.

Key Takeaways

• Three-dimensional printing is a supportive surgical planning technology, not a substitute for surgical expertise.
• Patient-specific models are particularly valuable in complex hip and proximal femoral deformities.
• Physical simulation can improve understanding of deformity and allow comparison of different reconstructive strategies before surgery.
• Different pelvic osteotomies produce different patterns of acetabular correction, emphasizing the importance of individualized surgical planning.
• Three-dimensional printing has potential applications in:
  • Preoperative planning.
  • Surgical simulation.
  • Resident education.
  • Research.
  • Patient communication.
  • Customized implant development.
• Current evidence is promising but remains limited by small study populations and heterogeneous study designs.
• The greatest potential benefit lies in combining advanced technology with sound clinical judgment and surgical skill.