PERIPROSTHETIC FRACTURES

1. PERIPROSTHETIC FRACTURES MehdiAbbasi M.D Shariati hospital

2. P.P.F increases in frequency • P.P.F often increase in osteoporotic bone, making stable fixation even more problematic

3. Mechanisms of injury • Low-energy falls are the mechanisms of injury in most patients • According to last Swedish registry at least 75% of P.P.F occur postoeratively • Spontaneous P.P.F is more common after revision surgery • High energy trauma accounts for only a small percentage of P.P.F and these types are associated with a more comminution

4. Mechanisms of injury • Intraoperative P.P.F occur more commonly during revision procedures • Given the predominance of low-energy injury mechanisms, associated injuries are uncommon

5. History • History should include: • Date of implantation • Used prosthesis • Arthroplasty complication such as infection • Functional state of patient, any recent changes in status or symptoms related to the arthroplasty can be a clue to heighten suspicion of subtle P.P.F or prefracture implant loosening

6. Physical exam • Prior surgical wound • Presence or absence of associated lesions

7. Imaging • A.P and lateral views of joint and full length of bones above and below the joint • Attention should paid to fractures , prosthesis(loosening), osteolysis, cortical erosion cortical penetration and notching • Diagnosis of intraoperative fractures can be from direct observation, but intraoperative radiograph should be obtained

8. Incidence and risk factor • 300000 T.K.A per year • 0.3% to 2.5% P.P.F in primary T.K.A • Up to 38% P.P.F in revision T.K.A • Patient-specific risk factors: • R.A • Osteolysis • Osteopenic bone • Frequent falls • Technique-specific risk factors

9. Incidence and risk factors • Osteopenia is a major contributing factor of P.P.F • B.M.D in the distal of femur decrease 19-44% one year after T.K.A • Stress fracture in the femur and tibia have been described after T.K.A . The patient complains of sudden pain without trauma and sign of infection • Periodic X.R and early bone scan are diagnostic • Local factors : osteolytic lesion, anterior femoral notching • P.S femoral component increases risk for intraoperative fracture

10. Classification of P.P femur fracture • Lewis and rorabek classification

11. Classification of P.P femur fracture • Su et al classification

12. treatment • Nonoperative treatment for displaced fractures has been associated with poor results. • Internal fixation: • traditional condylar buttress type plate is prone to complication • Traditional fixed angle plate constructs such as condylar plate reduces varus collapse but have limited application. • Modern methods of fixation, locked plating and retrograde nailing, provide superior results

13. treatment • Bicondylar and unicondylar locked screw fixation provide excellent distal fixation. • Retrograde intramedulary nailing can be applied to P.P.F that have adequate distal bone stock. It is preferred method by some authors.

14. Revision knee arthroplasty • For patient with loose implant associated with a P.P.F or inadequate bone stock to achieve fixation, revision is considered • In patient with a loose implant or a history of prefracture pain, occult infection should be ruled out. • Revision T.K.A with intramedulary femoral stem that engage the diaphysis and simultaneously stabilize the fracture can be used • Distal femoral replacement megaprosthesis have been used for salvage of failed internal fixation of P.P.F • For a younger, active patient an allograft prosthetic composite may be a better alternative

15. Periprosthetic fracture of tibial and patella • Incidence: • They are less common than femoral side • According to myoclinic joint registry (1999) incidence of P.P.F after primary T.K.A is 0.4% in the tibia 0.7% in the patella and 0.9% in the femur • The frequency of P.P.F in revision surgery is higher

16. Patella • Patellar fracture is the second most frequent P.P.F around the knee. • About 12% of reported fractures were directly associated with trauma. The remaining occurred spontaneously and most fractures occur during first 2 years after arthroplasty . • Etiologic factors specific to the patella are component design, excessive resection of bone , limb and prosthesis alignment and lateral release .

17. Classification of patellar fractures

18. Classification of Tibial fractures

20. Patellar fracture treatment • Patellar fracture treatment: no operative – ORIF –component resection patellectomy . • When extensor mechanism is intact , conservative management is recommended . • Surgical management is reserved for disturbance of extensor mechanism integrity , a loose patellar component and patellar maltracking. • ORIF with T.BW or cerclage wiring results in nonunion with an average nonunion rate of 82% • Therefore operative management is not an unreasonable consideration even in the face of a disrupted extensor mechanism.

21. Patellar fracture treatment • The presence of fracture and a loose implant is associated with high complication rates regardless of treatment method. • When there is adequate bone stock (>10mm) revision of the patellar component is reasonable. • Severe bone loss mandates patellar resection arthroplasty . • Extensor lag about 10˚ and a limitation of 20˚-30˚ of flexion are common.

22. TIBIA • P.P.F of tibia are uncommon • Most often they are associated a loose tibial component therefore revision is preferred in these situations. • Tibial revision for P.P.F requires the routine use of stem end augment and metaphysical filling metal implants. • The surgeon should be aware that isolated tibial component revision is rare, and commonly, should be prepared to revise the entire arthroplasty. • When arthroplasty component is stable , locked plate is preferred method of treatment.