Radiologic Assessment of Total Hip Arthroplasty: Loosening

Transcription

1 March 2004 Radiologic Assessment of Total Hip Arthroplasty: Loosening Grant Garrigues, Harvard Medical School

2 Anatomy Liner Acetabular Component Calcar Stem Femoral Component 2

3 Patient JQ 67 year-old man Left THA 10 years ago Hip/thigh pain What do you see? Position Lucencies Density 3 PACS, MGH

4 Implant loosening >500,000 THA and TKA each year in US 10% are revisions of failed implants Overall, very successful Aging population, obesity, more THA, younger patients vs. Improved surgical technique, implant design, and pharmacotherapy Bauer TW et al. Skeletal Rad,

5 Total Hip Complications Short-term Deep Venous Thrombosis (fatal PE, 0.3%) Nerve Palsies (1.7%) Vascular Complications (0.25%) Fracture/Perforations Dislocation (2-2.5%) Leg-length Discrepancy Long-term Namba RS et al. Current Ortho, Loosening (10%) Infection (1-5%) Heterotopic Ossification (significant, 8%) 5

6 Radiologic Assessment Assessment of long-term complications Loosening is the most significant Plain films: great bone/metal visualization Radiographic features Peri-implant lucency > 2mm Describe using Gruen Zones (following slide) Stress views / Interval change in position 6 Keogh CF et al. AJR 2003.

7 Gruen Zones 7

8 Other Modalities Arthrography Effective joint space visualized Aspirate and Biopsy CT and MRI Metal artifact US and Nuclear medicine Select applications Keogh CF et al. AJR Keogh CF et al. AJR White Griffiths LM HJ et et al. al. Radiology Clin

9 Ddx of Radiographic Loosening Peri-implant bone loss Aseptic loosening Infection Stress Shielding / Adaptive remodeling Aging / Osteoporosis Mechanical Failure Catastrophic Interfacial Bauer TW et al. Skeletal Rad, Tiggles S et al. AJR,

10 Aseptic Loosening Most common cause of TJR failure Wear debris Most generated at the articulating surface Submicron UHMWPE, HA, TiAlV, CoCr particles Spread throughout the effective joint space Phagocytosed by macrophages Induces bone resorption (osteolysis) Formation of fibrous, granulomatous tissue Willert and Semlitsch JBMR Shanbhag, et al. JOR

11 Aseptic Loosening Macrophages phagocytose wear debris, leading to two processes. Interfacial Membrane FBGC with wear debris Bone Resorption Osteoclast in Howship s lacuna Courtesy of Arun Shanbhag, MD 11

12 Head displacement: Millions of submicron polyethylene particles created with each step 12 Courtesy of Ferris Hall, MD

13 Aseptic Loosening Wear debris is the prevailing theory Hydrodynamic pressure may also contribute to aseptic loosening Early loosening from periprosthetic bone loss Trauma, chemicals, and thermal damage Joint pressures >700 mmhg Pumping action of loosened implants May cause aseptic loosening without particles Similar to mechansim of subchondral cysts in OA Aspenberg P et al. Acta Ortho Mjoberg B et al. Ortho

14 Aseptic Loosening Sequellae Painful loosening Revision arthroplasty Pathologic fractures Osteolysis leading to pathologic avulsion fracture Berry DJ J Arthro PACS, MGH

15 Septic Loosening Less common today Laminar flow OR UV lights Prophylactic Antibiotics Foreign body nidus Pathogens adhere to biomaterials S. epidermidis produces glycocalyx 15

16 Septic Loosening Radiographs mimic aseptic loosening Dx often with arthrogram and clinical correlation Peri-implant bone loss Sinus tracts Joint fluid aspiration: (culture, gram stain, etc.) Synovial biopsy Nuclear Med Tc-99m nonspecific In-111 leukocytes preferred Keogh CF et al. AJR, Griffiths HJ et al. Rad Clin, Arthrogram: sinus tracts and abcesses Keogh CF et al. AJR,

17 Septic Loosening Sequellae Painful implant loosening Revision arthroplasty Sterilize site before reimplantation Antibiotic impregnated cement spacers Sepsis, osteomyelitis, sinus tracts 17 Bauer TW et al. Skeletal Rad, 1999.

18 Stress Shielding Loading transferred from bone to stiffer prosthesis Proximal Stress Distal Stress Finite Element Analysis Interference Stress Interference + Load Stress 18 Friedman RJ et al. JBJS, Abaqus,

19 Stress Shielding Stress transferred through stem Metal is stiffer than bone Bypasses proximal periprosthetic bone Resorption of bone around proximal femoral shaft (Wolff s Law) More common in uncemented Increased risk of pathologic fracture Jacobs JJ et al. Ortho Clin Friedman RJ et al. JBJS, Keogh CF et al. AJR 2003.

20 Mechanical Failure Catastrophic failure is rare Fractured stem Shattered Zirconia ceramic heads Interface failure most common Cement fatigue fracture Debonding of cement-implant interface Porous coating fracture 20

21 Mechanical Failure Fractured Stem Keogh CF et al. AJR

22 Cement Fracture Debonding: implantcement interface is disrupted Courtesy of Ferris Hall, MD Subsidence: implant slides into medullary canal Cortical Reaction 22 Courtesy of Ferris Hall, MD

23 Porous Coating Fatigue Porous coatings, fiber-metal mesh, and other surfaces allow bone in-growth to cementless implants Multiple loose beads PACS, BIDMC Cross-section through fiber-metal mesh shows bone in-growth 23 PACS, BIDMC

24 Summary: JQ Aseptic Loosening of uncemented femoral component 67 year-old man Left THA Hip/thigh pain Volumetric wear Varus shift Subsidence Osteolytic Lesions Cortical Reaction Stress Fracture 24 PACS, MGH

25 Other THA Complications We have discussed loosening, the most common complication of THA, in detail. Bonus cases of other radiographically assessable complications follow 25

26 This is a powerful reminder of the possibility of fat emboli forced through bridging veins by manipulation in the meduallary canal. Cement Venogram: cement forced into vein before hardening Courtesy of Ferris Hall, MD Alastair et al. Brief report: fulminating fat embolism syndrome caused by paradoxical embolism through a patent foramen ovale, NEJM, 1993; 329(13):

27 Heterotopic ossification: This patient had a h/o spondylitis but any joint procedure has a small chance of this complication Courtesy of Ferris Hall, MD 27

28 References Aspenberg P, van der Vis H. Fluid pressure may cause periprosthetic osteolysis. Acta Orthop Scand, 1998; 69(1):1-4. Bauer TW, Schils J. The pathology of total joint arthroplasty. Skeletal Rad, 1999; 28: Berry DJ. Periprosthetic fractures associated with osteolysis. J Arthrop, 2003; 18(3, supl.): Friedman RJ, et al. Current concepts in orthopaedic biomaterials and implant fixation. JBJS, 1993; 75A(7): Griffiths HJ, et al. Total hip replacement and other orthopedic hip procedures in Rad Clinics of N America: Imaging of Orthopedic Hardware, 1995; 33(2): Jacobs JJ, Sumner DR, Galante JO. Mechanisms of bone loss associated with total hip replacement. Ortho Clin of N Amer; 1993; 24(4): Keogh CF, et al. Imaging of the painful hip arthroplasty. AJR, 2003; 180: Mjoberg B. The theory of early loosening of hip prostheses. Orthopedics, 1997; 20(12): Namba RS, et al. Adult reconstructive surgery in Current Diagnosis and Treatment in Orthopaedics, 3rd ed, Skinner HB ed.mcgraw-hill, Shanbhag A, et al. J Ortho R, 1994 Tigges S, et al. Complications of hip arthroplasty causing periprosthetic radiolucency on plain radiographs. AJR, 1994; 162: White LM, et al. Complications of total hip arthroplasty: MR imaging. Radiology, 2000; 215(1): Willert and Semlitsch. JBMR,

29 Acknowledgements Special Thanks to: Ferris Hall, MD Arun Shanbhag, PhD Harry Rubash, MD Pamela Lepkowski Larry Barbaras 29