FRACTURE FIXATION IN OSTEOPOROTIC BONE Stephen Kates, MD Hansj ӧ rg Wyss Professor of Orthopaedic Surgery Department of Orthopedics and Rehabilitation Associate Director, Center for Musculoskeletal Research University of Rochester Medical Center Michael Blauth Norbert Suhm Jorg Goldhahn THE AMERICAN GERIATRICS SOCIETY Geriatrics Health Professionals. Leading change. Improving care for older adults. AGS

LEARNING OUTCOMES Understand the factors influencing fixation in cortical and trabecular bone affected with osteoporosis What implant characteristics help with fixation? What aspects of surgical fixation are important? Understand basic metabolic bone work-up Slide 2

DEFINITIONS Insufficiency fracture: bone fails with normal weight-bearing Fragility fracture: result of a fall from a standing height or less Slide 3

CONTENTS Osteoporotic cortical bone  Biomechanical properties  Choice of implants  Surgical technique Trabecular bone  Biomechanical properties  Choice of implants  Surgical technique Slide 4

CONTENTS Osteoporotic cortical bone  Biomechanical properties  Choice of implants  Surgical technique Slide 5

BONE MASS CHANGES DURING LIFE Peak bone mass is reached at age 25 Heredity Medications Diet, tobacco, and alcohol Race / weight Slide 6

CONTENTS Osteoporotic cortical bone  Biomechanical properties  Choice of implants  Surgical technique Slide 7

LOCKED-PLATE PRINCIPLE Slide 8

by bending load PULLOUT OF REGULAR SCREWS Slide 9

SHEARING CONVENTIONAL PLATE OR SCREW DOWN Slide 10

RESISTANCE AGAINST BENDING LOAD Slide 11

RESISTANCE AGAINST BENDING LOAD IN LOCKED PLATE Plate-screw connection is solid Screw-bone interface Fails as a unit Slide 12

CONTENTS Osteoporotic cortical bone  Biomechanical properties  Choice of implants  Surgical technique Slide 13

UNI- VS. BICORTICAL SCREW FIXATION female Slide 14

Thin cortices: choose screw diameter as large as possible Slide 15 FAILURE WITH UNICORTICAL SCREWS

10 months postop. 5 days later Slide 16

+6% +18% +36% Load (N) 4.5 mm Cortex, bicortical 5.0 mm Locking, bicortical 4.0 mm Locking, bicortical 4.0 mm Locking, unicortical BIOMECHANICS: NORMAL BONE Slide 17

+17% +82% +91% Load (N) 4.5 mm Cortex, bicortical 5.0 mm Locking, bicortical 4.0 mm Locking, bicortical 4.0 mm Locking, unicortical BIOMECHANICS: OSTEOPENIC BONE Slide 18

BRIDGING WITH LOCKED IMPLANT Slide 19

CONCEPTS OF PLATE FIXATION IN OSTEOPOROTIC BONE ? compression technique Bridge plating useful Neutralization plates useful Long plate for bone protection Slide 20

CONTENTS Trabecular bone  Biomechanical properties  Choice of implants  Surgical technique Slide 21

OSTEOPOROSIS Normal bone Osteoporosis In osteoporotic metaphyseal bone: Fewer trabeculae for screws to engage Loss of critical bony interconnections Thinner internal support Slide 22

SIGNS YOUR PATIENT HAS POOR-QUALITY BONE Poor dentition: teeth are formed similarly to bone Multiple vertebral compression fractures Previous hip, radius, or tibial plateau fracture End-stage renal disease On steroid therapy Anticonvulsant use Slide 23

OSTEOPOROTIC TRABECULAR BONE: CLINICAL CONSEQUENCES Cut out Loss of screw fixation Spontaneous fractures Slide 24

CONTENTS Trabecular bone  Biomechanical properties  Choice of implants  Surgical technique Slide 25

Lag screw Helical blade Flat surface, increased area Slide 26 Less loss of bone with helical blade (right)

CHOICE OF IMPLANT: ONE FIXED ANGLE VS. MANY One fixed angle with blade plateMultiple fixed angles, longer implant Elderly woman who fell down one step Slide 27

VARUS COLLAPSE DUE TO LACK OF MEDIAL BUTTRESS Slide 28

CONTENTS Trabecular bone  Biomechanical properties  Choice of implants  Surgical technique Slide 29

INTRA-OP IMPACTION Slide 30

Augmentation to Improve Screw Fixation Enlarges the bone implant surface area NOT FDA APPROVED ! Slide 31

AUGMENTATION IN PRACTICE 32 Slide 32

IF BONE IS VERY POOR, CONSIDER PROSTHETIC REPLACEMENT Slide 33

DON’T FORGET THE SOFT TISSUES The wound must heal also Skin is also 98 years old Slide 34

BASIC OSTEOPOROSIS WORK-UP: METABOLIC 25-OH vitamin D level Intact PTH level Calcium Phosphate TSH Albumin level Slide 35

RADIOLOGIC WORK-UP OF OSTEOPOROSIS: DEXA SCAN DEXA is gold standard  T score is comparison to normal young bone  Z score is comparison to peers Treat with fragility fracture and osteoporosis, osteopenia Slide 36

VITAMIN D REPLETION Vitamin D2 50,000 units PO  Level 0  10 ng/dL: 3 times / week  Level 11  20 ng/dL: 2 times/week  Level 21  32 ng/dL: 1 time/week For 6  12 weeks, then recheck level Maintain with vitamin D IU/day Slide 37

TREATMENTS AFTER VITAMIN D REPLETION For viable patients:  Bisphosphonates  Selective estrogen receptor modulators (SERMs)  Parathyroid hormone Don’t forget the bone itself: treat the osteoporosis or refer Slide 38

TAKE-HOME MESSAGES Age & bone quality affect cortical and trabecular bone in different ways Absolute stability often not possible Principles of fixation:  Angular stability  Fracture reduction  Long bridging plates  Enlarged surface area of implant / bone  Augmentation  Prosthetic replacement Slide 39

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