Postoperative Complications of Total Knee Arthroplasty

1. Postoperative Complications of Total Knee Arthroplasty Presented by Spencer F. Schuenman, D.O.

2. Complications of TKA • Infection • Medical Complications • cardiovascular disease • diabetes mellitus • renal disease • pulmonary disease

3. Surgical Complications • incorrect alignment • ligamentous laxity • flexion contractures • extensor mechanism problems • Wound Healing • Neurovascular complications

4. Thromboembolism • Fat Embolization • Fracture • Device Failure

5. Infection • Incidence-has been reported to be less than 1 % with resurfacing arthroplasty and as high as 16% with hinged implants

6. Etiology-the host response is influenced by such factors as: rheumatoid arthritis, diabetes mellitus, poor nutrition, extreme old age, and obesity.

7. The size, design, and type of fixation of the prosthesis may also influence the incidence of sepsis. • A hinged metal-on-metal prosthesis has an infection rate as much as 20 X higher than metal-on-plastic. • Monomeric methyl methacrylate has been shown to impair leukocyte chemotaxis and phagocytosis

8. Surgical Technique and Environment • Hemostasis, shorter operating time, use of previous surgical incisions, decreased traffic in the OR, will help minimize postoperative sepsis.

9. Diagnosis-this is similar to that of diagnosing infection in THA. • Pain, prolonged drainage, decreased ROM, temp. elevation may all be present with sepsis. • Arthrocentesis, bone scan, and the indium labeled scan are all used in detecting sepsis.

10. Microorganisms-Staphylococcus, Streptococcus, E. Coli, Pseudomonas, and anaerobes make up the majority of pathogens.

11. Treatment-Aggressive debridement, removal of hardware, and parental antibiotics remain the mainstay of treatment. • Reimplantation can be performed if consecutive negative cultures are present. If sepsis cannot be controlled, an arthrodesis is then performed.

12. Medical Complications • Medical complications are much more common than surgical complications. It is necessary to work with a skilled internist during perioperative management and to take great care on positioning the patient during the procedure and postoperatively.

13. Surgical Complications • Good surgical technique and the use of proven components help in preventing complications of incorrect alignment, ligamentous laxity, flexion contractures, and extensor mechanism problems.

14. Wound Healing • Clinical factors that adversely affect wound healing: obesity, rheumatoid arthritis, diabetes mellitus, and tobacco smoking.

15. Choice of surgical incision is important; preexisting incisions should be utilized whenever possible to prevent skin necrosis between the old and new incision. • Wound drainage should be treated aggressively.

16. Neurovascular Complications • This complication occurs infrequently in TKA. Local cutaneous nerves, especially laterally often result in decreased sensation.

17. The major neurological complication with TKA is peroneal nerve palsy. This occurs in less than 1% of cases. • Treatment includes: flexion of knee, removal of any tight dressings over the nerve, and by use of an ankle-foot orthosis, if a significant deficit is noted. • A sensory deficit has a better prognosis than a combined sensory-motor deficit.

18. Arterial vascular injury is very infrequent with an incidence of about 0.03%. The most common etiology is use of the tourniquet over an atherosclerotic vessel which causes subsequent embolization.

19. Postoperative pain out of proportion which is unresponsive to narcotic therapy should raise concern for arterial compromise. Immediate arteriography and vascular surgical consultation should be obtained.

20. Thromboembolism • Prospective studies have shown an incidence of thrombosis of 50 to 70%. Location is primarily in the calf veins, but the popliteal and femoral veins are involved in 5 to 10%.

21. Bilateral TKA has shown an incidence of increased thromboembolism. • A recent survey at the Mayo Clinic comparing TKA and THA revealed more instances of pulmonary emboli after TKA than THA.

22. Prophylaxis includes: early motion of the knee, antiembolism stockings, SCDs, Warfarin, and low-molecular-weight heparin.

23. Fat Embolization • Primarily seen with use of long-stemmed implants or intramedullary instrumentation for limb alignment. • This is a very infrequent complication in TKA.

24. Fracture • Periprosthetic fractures post TKA are also very infrequent • The etiology of these fractures is osteoporosis, notching of the anterior femoral cortex, and trauma.

25. Device Failure • Implant breakage and failure was initially related to specific designs. • Of greater concern at present is failure of the polyethylene as a bearing surface. The polyethylene thickness should be a minimum of 8mm to avoid problems with polyethylene failure.

26. Summary • A thorough preoperative evaluation and consultation with appropriate specialists will avoid many postoperative medical complications. Careful surgical technique will avoid many postoperative surgical complications.

27. Aggressive management of postoperative complications is essential to prevent further difficulties such as postoperative wound sepsis. The goal of wound healing must take priority over achieving postoperative knee motion. Correct limb alignment must be obtained to maintain an appropriately functioning arthroplasty.