I. Total Hip Arthoplasty
A. Fractures of the acetabulum
1. Epidemiology/overview
a. The incidence of periprosthetic fracture of the acetabulum occurring during primary total hip arthroplasty (THA) with cemented acetabular components is 0.2%. With cementless acetabular components it is 0.4%.
b. Intraoperative fractures typically occur during cup impaction.
2. Risk factors
a. Intraoperative risk factors
i. Cementless acetabular component (press-fit)
ii. Underreaming by >2 mm
iii. Elliptical monoblock components
iv. Osteopenia/osteoporosis
v. Paget disease
vi. Removal of acetabular component at revision
b. Postoperative risk factors
i. Trauma
ii. Osteolysis
iii. Osteopenia/osteoporosis
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3. |
History and physical examination—Suspect postoperative fracture if groin pain is present after trauma. |
4. Imaging studies
a. Plain radiographs
i. Plain radiographs may underestimate bone loss.
ii. Judet views (obturator and iliac oblique radiographs) may be helpful in identifying an anterior or posterior column fracture.
iii. The fracture line may be obscured by metallic components.
b. Bone scan
i. Bone scans may be helpful in identifying late fractures not seen on plain radiographs.
ii. Bone scans may show areas of increased up-take for 1 to 2 years postoperatively in the absence of fracture.
c. CT scanning is seldom needed, but it may help visualize fractures not identified by other imaging methods.
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4. |
Classification—The Paprosky classification of periprosthetic fractures of the acetabulum associated with THA is shown in Table 1. |
5. Treatment
a. Type I (intraoperative fracture secondary to acetabular component insertion)
i. Type IA (fracture of acetabular wall recognized intraoperatively, fracture nondisplaced and component stable)—Leave cup and augment with multiple screws through the cup; consider protected weight bearing for 8 to 12 weeks.
ii. Type IB (fracture recognized intraoperatively and displaced)—Cup should be removed. Bone screws (cancellous) are used to fix the displaced fragment. Use a buttress plate if the posterior column is involved. Re-ream close to component size (minimize underreaming). Carefully impact component back into position. Consider protected weight bearing for 8 to 12 weeks.
iii. Type IC (fracture not recognized intraoperatively)—Management is the same as for type III, IV, or V (described later in this section).
[Table 1. Paprosky Classification of Periprosthetic Fractures of the Acetabulum Associated with THA]
b. Type II (intraoperative fracture secondary to acetabular component removal)—May use a large revision acetabular component with multiple screws if 50% of the remaining host bone retains structural integrity and if areas of primary support for the cup remain intact.
c. Type III (traumatic fracture)
i. Type IIIA (component stable)—Leave cup; consider protected weight bearing for 8 to 12 weeks.
ii. Type IIIB (component unstable)—Revise to porous revision acetabular component with multiple screws. If posterior column fracture is present, fix with pelvic plate and screws before acetabular component insertion.
d. Type IV (spontaneous fracture)
i. Type IVA (associated with loss of <50% of acetabular bone stock)—May use a large revision acetabular component with multiple screws; use bone graft as needed.
ii. Type IVB (associated with loss of >50% of acetabular bone stock)—Use bulk allograft (eg, pelvic allograft or figure-7-shaped distal femoral allograft) or metallic augment(s) to manage bone defect. May need pelvic plate and screws to restore column stability. Use cage or cup-cage construct if host bone is insufficient to allow bone ingrowth. Do not fix pelvic fracture by using only an acetabular component with screws that secure the major bone fragments.
e. Type V (pelvic discontinuity)
i. Type VA (associated with loss of <50% of acetabular bone stock)—Fix posterior column fracture with pelvic plate and screws before acetabular component insertion; revise to porous revision acetabular component with multiple screws. Bone-graft the fracture site. Consider protected weight bearing for 8 to 12 weeks.
ii. Type VB (associated with loss of >50% of acetabular bone stock)—Fix discontinuity with pelvic plate and screws. Use bulk allograft (eg, pelvic allograft) or metallic augment(s) to manage bone defect. Use cemented acetabular component or cage construct that spans from ilium to ischium.
iii. Type VC (associated with prior pelvic radiation)—Management is the same as for type VB (shown above). Ability to heal fracture and achieve biologic fixation of a porous cup is very poor. Use cemented acetabular component or cage construct that spans from ilium to ischium.
[
Table 2. Vancouver Classification of Intraoperative Periprosthetic Fractures of the Femur Associated with THA as Modified by Duncan and Masri]
B. Fractures of the femur
1. Epidemiology/overview
a. The incidence of intraoperative periprosthetic femoral fracture in primary THA is 0.1% to 5.4%; in revision THA it is 3% to 20.9%.
b. Trauma is the most commonly cited cause of periprosthetic fractures of the femur.
2. Risk factors
a. Revision (higher risk than primary THA)
b. Cementless press-fit technique (versus cemented technique)
c. Compromised bone stock (osteolytic defect or osteoporosis)
d. Impaction grafting technique (Prophylactic cerclage wires and cortical onlay strut allografts are recommended to help reduce this risk.)
3. Imaging studies
a. Plain radiographs
i. Obtain a minimum of two views (AP and lateral) to help identify the type and extent of the fracture. Assess radiographs for cortical perforations, longitudinal splits, displaced fracture fragments, comminution, and signs of component instability.
ii. The fracture line may be obscured by a metallic component.
b. Bone scan
i. Bone scans are typically not needed, but they may be helpful in identifying late fractures not seen on plain radiographs.
ii. Bone scans may show areas of increased up-take for 1 to 2 years postoperatively in the absence of fracture.
[
Table 3. Vancouver Classification of Postoperative Periprosthetic Fractures of the Femur Associated with THA as Modified by Duncan and Masri]
4. Classification
a. Numerous classification schemes have been described for periprosthetic fractures of the femur associated with THA.
b. The Vancouver classification system, as modified by Duncan and Masri, is the most widely used.
i. This system is simple and reproducible, and it has been validated. It also provides useful guidelines for management.
ii. The Vancouver classification of periprosthetic fractures of the femur was recently updated by Duncan and Masri to include classifications for intraoperative (Table 2) and postoperative (Table 3,
Figure 1) periprosthetic fractures.
[Figure 1. Vancouver classification of postoperative periprosthetic fractures of the femur associated with THA as modified by Duncan and Masri. Type A: Fracture is located in the trochanteric region (type AG fractures are located in the greater trochanter and type AL fractures are located in the lesser trochanter). Type B1: Fracture is located around or just distal to the femoral stem, and the stem is well fixed. Type B2: Fracture is located around or just distal to the femoral stem, the stem is loose, and there is good bone stock in the proximal femur. Type B3: Fracture is located around or just distal to the femoral stem, the stem is loose, and there is poor bone stock in the proximal femur. Type C: Fracture is located well below the femoral stem.]
5. Treatment
a. Intraoperative fracture
i. A stable femoral shaft fracture (minimally displaced proximal longitudinal split) that is not recognized intraoperatively during THA, but that is seen on postoperative radiographs and is not affecting component stability, can be managed with protected weight bearing until union occurs.
ii. Type A (proximal metaphyseal fracture, not extending into the diaphysis)
(a) Type A1 (cortical perforation)—Treat with local bone graft (eg, acetabular reaming) or ignore if unlikely to compromise component stability.
(b) Type A2 (nondisplaced linear crack)—Treat with cerclage wiring. May need to back out cementless stem first, cerclage fracture, then reinsert stem.
(c) Type A3 (displaced or unstable fracture of the proximal femur or greater trochanter)—Treat with diaphyseal fitting cementless stem. Open reduction and internal fixation (ORIF) trochanter if needed.
iii. Type B (diaphyseal fracture, not extending into the distal diaphysis)
(a) Type B1 (cortical perforation)—Bypass with longer stem by two cortical diameters. Consider cerclage fixation distal to perforation to prevent fracture propagation.
(b) Type B2 (nondisplaced linear crack)—Cerclage fixation to prevent fracture propagation. Bypass with longer stem by two cortical diameters if possible. Consider use of cortical strut grafts.
(c) Type B3 (displaced fracture of the midfemur)—Expose, reduce, and ORIF fracture with cerclage wires and/or cortical strut grafts. Bypass fracture with longer stem by two cortical diameters if possible.
iv. Type C (distal diaphyseal fracture extending beyond the longest extent of the longest revision stem, can include the distal metaphysis)
(a) Type C1 (cortical perforation)—Treat with bone grafting and placement of cortical strut graft.
(b) Type C2 (nondisplaced linear crack extending just above the knee joint)—Treat with cerclage wires. Strongly consider use of cortical strut graft as well.
(c) Type C3 (displaced fracture of the distal femur, cannot be bypassed by a femoral stem)—ORIF of fracture (using plate and screw construct)
b. Postoperative fracture
i. Type A (fracture is located in the trochanteric region)
(a) Type AG (fracture in greater trochanter)—Treat symptomatically with protected weight bearing; limit abduction. Consider ORIF if fracture is displaced >2.5 cm or if there is pain, instability, or abductor weakness due to trochanteric nonunion.
(b) Type AL (fracture in lesser trochanter)—Treat symptomatically with protected weight bearing even if fracture is displaced. Treat surgically only if a large portion of the medial cortex is attached.
ii. Type B (fracture is located around or just distal to the femoral stem)
(a) Type B1 (fracture is around or just distal to the femoral stem and the stem is well fixed)—Treat with ORIF with fixation in two planes (lateral and anterior). May use any combination of plates and cortical strut grafts. Insert cable plate system with cerclage wires/cables proximal and screws distal to the stem. Secure cortical strut grafts with wires/cables. Locking plates may also be used and can include proximal unicortical screws.
(b) Type B2 (fracture is around or just distal to the femoral stem, the stem is loose, and there is good bone stock in the proximal femur)—Treat with long-stem revision. Consider cortical strut grafts to improve stability and enhance bone stock.
(c) Type B3 (fracture is around or just distal to the femoral stem, the stem is loose, and there is poor bone stock in the proximal femur)—Treat with long-stem revision. Consider allograft-prosthetic composite in a young patient to help augment bone stock. Consider proximal femoral replacement (tumor-type) component in elderly or low-demand patients.
iii. Type C (fracture is located well below the femoral stem)—Treat with ORIF. Manage with blade plate, condylar screw plate, or locking supracondylar plate (eg, less invasive stabilization system [LISS]). Overlap plate and stem to avoid creation of a stress riser. Use screws to secure plate distal to the stem. Use cerclage wires around the plate at the level of the stem. May consider treatment with a retrograde intramedullary nail, but this may create a stress riser between the femoral stem tip and the nail.
II. Total Knee Arthroplasty
A. Fractures of the distal femur
1. Epidemiology
a. The incidence of periprosthetic fracture of the distal femur in total knee arthroplasty (TKA) is 0.3% to 2.5%.
b. The incidence after revision TKA is higher.
2. Risk factors
a. Rheumatoid arthritis
b. Neurologic disorders
c. Chronic steroid therapy
d. Osteopenia/osteoporosis
e. Anterior femoral notching
i. Biomechanical studies have shown that notching during femoral preparation weakens the anterior femur at the bone-component interface; therefore, it should be avoided.
ii. The effect of notching has been debated. Although notching decreases the fracture resistance of the distal femur, it does not necessarily equate with a higher risk of supracondylar femur fracture.
3. Imaging studies
a. Plain radiographs
i. Obtain a minimum of two views (AP and lateral) to help identify the type and extent of the fracture. Assess radiographs for signs of component loosening.
ii. The fracture line may be obscured by a metallic component.
b. Bone scan—A bone scan may help identify a fracture when plain radiographs are not diagnostic.
4. Classification—Several classification systems have been described for supracondylar periprosthetic fractures of the distal femur associated with TKA (
Table 4), including Su and associates' anatomically based system (
Table 5,
Figure 2).
5. Treatment
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a. |
Nonsurgical treatment—Consider nonsurgical treatment of nondisplaced fractures in poor surgical candidates. |
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b. |
Surgical treatment—Most fractures should be managed surgically. This allows for early range of motion, avoids prolonged immobilization, and reduces the risk of fracture displacement. |
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i. |
Loose femoral component—If the femoral component is loose, perform revision knee |
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[Table 4. Classification of Supracondylar Periprosthetic Fractures of the Distal Femur Associated With TKA (Based on Displacement)]
[Table 5. Su and Associates' Classification of Supracondylar Periprosthetic Fractures of the Distal Femur Associated with TKA (Based on Fracture Location)]
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arthroplasty with a stemmed component. A distal (tumor-type) femoral replacement component may be considered if the remaining bone stock is very poor. Consider letting the fracture heal first, then revising once bony union has occurred. |
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ii. |
Stable/intact femoral component—If the femoral component is stable/intact, Su and associates' classification (Table 5, Figure 2) can be helpful in guiding treatment. |
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iii. |
Treatment according to Su and associates' classification a. Type I (supracondylar fracture proximal to femoral knee component)—Treat with antegrade or retrograde intramedullary nail (if the femoral knee component has an open-box design to allow insertion). Alternatively, ORIF with a fixed-angle device (such as a blade plate, condylar screw plate, or locking supracondylar plate) can be used. b. Type II (supracondylar fracture originates at the proximal aspect of the femoral knee component and extends proximally)—Treat with retrograde intramedullary nail (if the femoral component has an open-box design to allow insertion). Alternatively, a fixed-angle device (such as a blade plate, condylar screw plate, or locking supracondylar plate) can be used. c. Type III (supraconlylar fracture, any part of the fracture line is distal to the upper edge of the anterior flange of the femoral knee component)—Treat with a fixed-angle device (such as a blade plate, condylar screw plate, or locking supracondylar plate) if remaining bone attached to component is amenable to fixation. Alternatively, perform revision knee arthroplasty with stemmed component if the remaining bone is not amenable to fixation. A distal (tumor-type)
femoral replacement component may be considered if the remaining bone stock is very poor. |
6. Pearls and pitfalls—When using a retrograde intramedullary nail for fixation of a supracondylar fracture of the distal femur, the femoral component must have an opening large enough to allow nail insertion. Retrograde nail insertion may not be possible with some closed-box posterior stabilized femoral component designs.
B. Fractures of the tibia
1. Epidemiology
a. The incidence of periprosthetic tibia fracture in primary TKA is ≤0.7%.
b. The incidence in revision TKA is ≤0.9%.
2. Risk factors
a. Insertion of a long-stem component
b. Loose tibial component
c. Periprosthetic osteolysis
d. Malalignment of components
e. Component removal during revision
f. Tibial tubercle osteotomy
3. Imaging studies
a. Plain radiographs
i. Obtain a minimum of two views (AP and lateral) to help identify the type and extent of the fracture. Look for signs of component instability.
ii. The fracture line may be obscured by a metallic component.
b. Bone scan—Bone scans may be helpful in identifying late fractures not seen on plain radiographs.
4. Classification—Felix and associates' classification of periprosthetic fractures of the tibia associated with TKA is shown in
Table 6 and
Figure 3.
5. Treatment
a. Type I (fracture of tibial plateau)
i. Type IA (component well fixed)—Treat with brace or cast and protected weight bearing.
ii. Type IB (component loose)—Revise components, typically with a stem into the diaphysis.
iii. Type IC (intraoperative fracture)—If fracture is stable, may use brace and protected weight bearing. If fracture is unstable, perform ORIF and bypass with stem.
b. Type II (fracture adjacent to tibial stem)
i. Type IIA (component well fixed)—If fracture is nondisplaced, may use brace/cast and protected weight bearing. If fracture is displaced, manage with closed reduction and casting or consider ORIF.
[Table 6. Felix and Associates' Classification of Periprosthetic Fractures of the Tibia Associated With TKA]
ii. Type IIB (component loose)—Revise components to long-stem component, typically with a stem into the diaphysis.
iii. Type IIC (intraoperative fracture)—If fracture is stable, may use brace and protected weight bearing. If fracture is unstable, bone graft cortical defect and bypass with stem.
c. Type III (fracture of tibial shaft, distal to component)
i. Type IIIA (component well fixed)—If fracture is nondisplaced, may use brace/cast and protected weight bearing. If fracture is displaced, treat with closed reduction and casting or consider ORIF.
ii. Type IIIB (component loose)—Treat fracture first; revise components later. May revise early to long-stem tibial component if fracture is located more proximally.
iii. Type IIIC (intraoperative fracture)—If fracture is stable with acceptable alignment, may immobilize and use protected weight bearing. If fracture is unstable, manage with closed reduction and casting or consider ORIF.
d. Type IV (fracture of tibial tubercle)—These fractures are rare and typically do not compromise component stability. They may be treated with standard fracture management techniques.
[Figure 3. Illustration of periprosthetic fractures of the tibia associated with TKA as classified by Felix and associates. AP and lateral views are shown.]
C. Fractures of the patella
1. Epidemiology (Mayo Clinic)
a. The incidence of periprosthetic patellar fracture in primary TKA is 0.7%; almost all of these occur postoperatively.
b. The incidence in revision TKA is 1.8%; most of these occur postoperatively, but fractures can occur intraoperatively at the time of revision.
c. Two thirds of all periprosthetic fractures of the patella occur within 2 years after arthroplasty; such fractures are commonly related to osteonecrosis of the patella resulting from devascularization during surgery.
2. Risk factors
a. Patient-related factors
i. Obesity
ii. High activity level
iii. High knee flexion
iv. Thin patella
v. Osteopenia
vi. Rheumatoid arthritis
vii. Previous surgery
b. Component-related factors
i. Resurfaced patella
ii. Central single-peg component
iii. Inset patellar component
iv. Cementless fixation
v. Metal backing
c. Technical factors
i. Patellar maltracking
ii. Overresection or underresection of the patella
iii. Thermal necrosis
iv. Devascularization (lateral release, peripatellar dissection)
v. Femoral component malalignment
vi. Extensor mechanism malalignment
vii. Excessive quadriceps release
3. Imaging studies—Plain radiographs
a. Obtain AP, lateral, and skyline (ie, sunrise/Merchant) views
b. Look for signs of component instability, location of fracture, and status of extensor mechanism (look for a high- or low-riding patella).
4. Classification—Classification of periprosthetic fractures of the patella associated with TKA is shown in
Table 7.
5. Treatment
a. A fracture of the patella involving a resurfaced patella, even with some displacement, can be managed nonsurgically if the extensor retinaculum is intact.
b. Type I (extensor mechanism intact; patellar component stable)—Nonsurgical management is universally successful with bracing or cast treatment.
c. Type II (extensor mechanism disrupted with or without patellar component in place)—Remove patellar component. Treat fracture with ORIF (if amenable) with or without component revision. Repair and augment extensor mechanism (typically with allograft).
[Table 7. Classification of Periprosthetic Fractures of the Patella Associated with TKA]
d. Type III (extensor mechanism intact; patellar component unstable)—Remove patellar component. Manage fracture with ORIF, partial patellectomy, or total patellectomy.
6. Pearls and pitfalls
a. Adequate bone stock (>13 mm) is needed for standard patella resurfacing. Highly porous metal or bioconcave patellar components may allow resurfacing in cases of bone loss.
b. Treat a nonresurfaced patella as a typical traumatic patella fracture.
c. Attempt to preserve the patella to maintain the mechanical advantage of the quadriceps.
d. Consider tubularization of extensor mechanism or bone grafting in a synovial pouch for a patient with very poor bone stock and significant fracture comminution.
Top Testing Facts
Periprosthetic Fractures Associated With Total Hip Arthroplasty
1. Risk factors for an intraoperative fracture of the acetabulum include underreaming (typically >2 mm) and placement of a cementless acetabular component.
2. The presence of pelvic discontinuity necessitates fixation with pelvic plate and screws before insertion of the acetabular component.
3. A stable femoral shaft fracture (minimally displaced proximal longitudinal split) that is not recognized intraoperatively during THA, but that is seen on postoperative radiographs and is not affecting component stability, can be managed with protected weight bearing until union occurs.
4. Treatment of a postoperative Vancouver type B1 fracture of the femur (fracture is around or just distal to the femoral stem, stem is well fixed) is achieved by ORIF with cerclage and plate/strut construct.
5. Treatment of a postoperative Vancouver type B2 fracture of the femur (fracture is around or just distal to the femoral stem, stem is loose, good bone stock in the proximal femur) is achieved by revision with a long-stem component.
6. A postoperative Vancouver type C fracture of the femur (fracture is well below the femoral stem) can be treated independently with standard techniques of fracture fixation as if no component were present. Typical fixation often involves a lateral plate with screws distal and cerclage wires proximal with the plate overlapping the distal extent of the stem to prevent a stress riser.
Periprosthetic Fractures Associated With Total Knee Arthroplasty
1. A type I supracondylar fracture of the distal femur should be managed with an antegrade or retrograde intramedullary nail (if the femoral component has an open-box design to allow insertion). Alternatively, ORIF with a fixed-angle device (such as a blade plate, condylar screw plate, or locking supracondylar plate) can be used.
2. When using a retrograde intramedullary nail for fixation of a supracondylar fracture of the distal femur, the femoral component must have an opening large enough to allow nail insertion. Retrograde nail insertion may not be possible with some closed-box posterior stabilized femoral component designs.
3. Type I (tibial plateau) and type II (adjacent to the tibial stem) fractures of the tibia that involve loose prosthetic components are treated with revision of the components (typically with a stem into the diaphysis).
4. A fracture of the patella involving a resurfaced patella after TKA, even with some displacement, can be managed nonsurgically if the extensor retinaculum is intact.
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