60Patient Selection and Counseling 60 60

Chapter 60 · Patient Selection and Counseling – C. Mahoney, K. L. Garvin ³⁸¹

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60 Patient Selection and Counseling

C. Mahoney, K. L. Garvin

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Summary

When selecting patients for total knee replacement, it is important to assess both the chronological and the phys- iological patient age to gage longevity of the implant as well as perioperative co-morbidity risk. The severity of clinical and radiographic disease can factor into post- operative functional status and can also direct the sur- geons in their implant selection. The number of poten- tial complications has been reduced in recent years by optimizing the patient’s health prior to surgery. Inter- ventions such as preoperative antibiotics and aggressive postoperative DVT prophylaxis have also reduced the risk of complication. The surgeon considering total knee replacement in a patient needs to spend time with that patient to let him or her know about the expectations postoperatively as well as to summarize the risks of surgery.

Introduction

Total knee arthroplasty (TKA) is one of the most suc- cessful interventions in the treatment of patients with sig- nificant osteoarthritis of the knee. Criteria used by the surgeon to select patients for this operation significantly affect the success and longevity of the surgery. Factors that affect the success and durability of the implant in- clude the patient’s age, activity level, size, medical co- morbidities, and severity of clinical and radiographic arthritis.

At the time of selection for surgery,patients should be made aware of potential medical complications that can occur both during and after TKA.The most common and serious complications include perioperative mortality, infection, and deep venous thrombosis (DVT).

This chapter outlines criteria used to aid the surgeon in selecting appropriate candidates for TKA and also discusses the counseling of patients regarding possible complications that can occur around the time of surgery.

Patient Selection

The average age of patients in the United States receiving primary TKA for the treatment of arthritis of the knee is 69 years [1].Despite different activity levels corresponding with different ages, no consistent correlation has been found between patient satisfaction and patient age [2].

While the average age is 69 years, the percentage of pa- tients having primary total knee arthroplasty under the age of 60 is actually rising [1]. When age is considered, both the very young and very old require special attention.

Younger patients require special attention because they tend to show earlier wear and joint failure when com- pared with age-adjusted counterparts.The most likely rea- son for this is the higher activity level of younger patients.

Younger patients have higher levels of expectation and are usually healthier than older patients, which contributes to greater wear. When weighing surgical intervention in a patient under the age of 60, both osteotomy and uni- compartmental arthroplasty should be considered.

When examining younger patients, special attention should be given to the patient’s range of motion,history of previous surgery, varus or valgus malalignment, ligamen- tous stability, and to assessing all three compartments of the knee for both symptoms and radiographic evidence of arthrosis. Patients with flexion contractures greater than 15°, patients with greater than 10° of varus or 15° of valgus, and those with ligamentously deficient knees have histor- ically not done well with unicompartmental arthroplasty [3]. In the osteotomy patient, the presence of significant degenerative changes in the opposite compartment may lead to less than satisfactory results [4].

The results of TKA in patients under the age of 55 are

encouraging and in most studies exceed the results of

those patients who have had osteotomy or unicompart-

mental arthroplasty.Three studies of young patients with

an age range of 36-51 show good to excellent results in

anywhere from 93% to 100% [5-8]. Survivorship in two

of these studies was greater than 90% at a minimum of

10 years [5, 8]. Based on these data, TKA can currently

be safely considered for patients under the age of 55 as

long as they accept the risk of increased wear and earlier

failure rates.

While there is no true minimum age for doing a total knee replacement, there is certainly no maximum age af- ter which patients should be excluded. There are a num- ber of studies that show that mortalities do rise among older patients; however, there is a high correlation be- tween the number of medical co-morbidities and mor- tality [9]. Accepting that, there is no correlation between age and patient satisfaction, and therefore, healthy pa- tients into their 90s can be considered reasonable candi- dates for TKA.

The severity of preoperative arthritis in the knee does affect the long-term outcome of TKA.One of the most im- portant factors in postoperative satisfaction is the level of preoperative functional loss. Patients who have severe clinical and radiographic arthritis typically are more satisfied after TKA compared with patients who are less affected both radiographically and clinically [10]. How- ever, it is accepted that preoperative range of motion correlates relatively highly with postoperative range of motion, so those patients who do have severe disease and preoperative stiffness, while achieving high levels of sat- isfaction,may experience a postoperative range of motion which does not equal that of patients who are less affect- ed with severe clinical arthrosis and stiffness.

In severely deformed patients, there has been a high- er rate of success using a posterior-stabilized prosthesis.

Booth [11] has reported increased range of motion,greater stability,equal survival rates,and greater accommodations for joint line alterations using a posterior-stabilized im- plant compared with a cruciate-retaining implant. Based on these factors, we typically select a posterior-stabilized implant for all patients,but specifically for those who have severe radiographic and clinical arthrosis.

Postoperative medical complications are correlated with preoperative medical conditions [10]. Medical com- plications that can occur after TKA include DVT, superfi- cial or deep wound infection, seroma or hematoma for- mation, fat embolism, and numbness around the wound.

Patients should be advised that pre-existing medical con- ditions can be worsened by the procedure. Whether a clinical condition will become significantly worse de- pends on the preoperative status, the age of the patient, the skill of the surgeon, the anesthetic, and the preopera- tive medical workup. Only those patients who have had a full medical workup and for whom all medical issues have been completely addressed preoperatively should be con- sidered for total knee replacement [12-15].

Counseling

Prior to surgery, the patient and physician should discuss complications that may arise as a result of total knee re- placement. Those complications include death, venous thromboembolism, and infection [16]. A complete un-

derstanding of the potential complication achieves two goals. Initially, it allows the patient to make an informed decision about whether to have surgery. An open discus- sion will allow patients to feel that they are deciding along with the surgeon that total knee replacement is both a correct and a safe decision. Later, in the event of a com- plication, the patients and their families will have been prepared for the possibility that complications do occur despite our best efforts.

The most serious complication that occurs is death.

The overall 30-day mortality after total knee replacement is 0.21% [9]; the 90-day mortality is 0.46% [17]. Patients under the age of 65 have a significantly reduced mortali- ty compared with those older than 85 years.The under-65 rate is 0.13%, while those over the age of 85 have an ap- proximately 4.65% 90-day mortality [17]. Significant pre- existing co-morbidities do result in higher mortality.This has been estimated to be as high as 16 times greater than for patients without medical co-morbidities.As discussed above, older patients typically have more medical prob- lems and, therefore, the morbidities themselves are likely the cause of most deaths.

The most common complication experienced in total knee replacement is venous thromboembolism [18]. The prevalence of DVT without prophylaxis in TKA has been estimated anywhere from 40% to 84%,with symptomatic pulmonary emboli ranging from 1.8% to 7%. Based on these percentages, most surgeons take preventive mea- sures that can include blood thinners,pressure stockings, early motion after surgery, or compression devices.

Patients should be counseled that the risk of having a clot can be dramatically reduced with a combination of the interventions listed above.Regardless of the type,this risk can be reduced, but not eliminated.

Aside from death, deep infection after TKA is the most serious and debilitating complication that can oc- cur. With standard prophylaxis, including perioperative antibiotics, laminar air flow, and body exhaust suits, in- fection rates should not exceed 2%.Patients with rheuma- toid arthritis, previous open surgeries, immunosuppres- sive therapy,poor nutrition,diabetes,renal failure,and al- cohol abuse have all been shown to have higher infection rates. Patients with psoriatic arthritis also have higher rates of infection; psoriatic lesions should be avoided if possible when making incisions. When counseling patients regarding the risk of infection,the hospital’s sur- gical infection rate is a useful number for the patient.

Again,patients should be counseled that while the chance of infection cannot be eliminated, it can be reduced with careful attention to detail and state-of-the-art surgical practice. The surgeon can also lower the risk by complet- ing the surgery in an expedient fashion that minimizes soft-tissue trauma.

The operating time, amount of dissection, and reha- bilitation potential are all affected by the patient’s habi-

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tus. Obese patients require more dissection and extra re- traction during surgery.This leads to increased operating time. The mobility of the adipose tissue should be as- sessed preoperatively.Patients with loose or mobile fat are much easier to operate on, as their soft tissue can be re- tracted very readily. Patients with body mass indices (BMIs) that are equal but who have tight fat require more dissection and retraction. Obese patients also have an in- creased risk of wound-healing problems. All these issues should be addressed preoperatively with the patient.

References

1. National Center for Health Statistics (1997) Nationwide Inpatient Survey:

Osteoarthritis of the knee group defined as individuals who had an ICD-9 CM diagnosis that was classified as osteoarthritis and any listed diagnosis that was classified as applying to the knee region. In: AAOS Manual (2002) Osteoarthritis of the Knee: a Compendium of Evidence- based Information and Resources

2. Robertsson O, Dunbar M, Pehrsson T, Knutson K, Lidgren L (2000) Patient satisfaction after knee arthroplasty: a report on 27,372 knees operated on between 1981 and 1995 in Sweden. Acta Orthop Scand 71:262-267 3. Tria AJ (2004) Unicondylar knee arthroplasty - the MIS technique. Amer-

ican Academy of Orthopedic Surgeons Annual Meeting, San Francisco, March 10-14

4. Hanssen AD (2001) Osteotomy about the knee: American perspective. In:

Insall JN, Scott WN (eds) Surgery of the knee, 3rd edn. Churchill Living- stone, New York, pp 1447-1464

5. Diduch DR, Insall JN, Scott WN, Scuderi GR, Font-Rodriguez D (1997) Total knee replacement in young, active patients. Long-term follow-up and functional outcome. J Bone Joint Surg [Am] 79:575-582

6. Dalury DF, Ewald FC, Christie MJ, Scott RD (1995) Total knee arthroplasty in a group of patients less than 45 years of age. J Arthroplasty 10:598-602 7. Mont MA, Lee CW, Sheldon M, Lennon WC, Hungerford DS (2002) Total knee arthroplasty in patients ≤50 years old. J Arthroplasty 17:538-543 8. Ranawat CS, Padgett DE, Ohashi Y (1989) Total knee arthroplasty for

patients younger than 55 years. Clin Orthop 248:27-33

9. Parvizi J, Sullivan TA, Trousdale RT, Lewallen DG (2001) Thirty-day mortal- ity after total knee arthroplasty. J Bone Joint Surg [Am] 83:1157-1161 10. Heck DA, Robinson RL, Partridge CM, Lubitz RM, Freund DA (1998) Patient

outcomes after knee replacement. Clin Orthop 356:93-110

11. Booth RE (2001) The posterior stabilized: a knee for all seasons. Orthope- dics 24:887-888

12. Ansari S, Warwick D, Ackroyd CE, Newman JH (1997) Incidence of fatal pulmonary embolism after 1,390 knee arthroplasties without routine prophylactic anticoagulation, except in high-risk cases. J Arthroplasty 12:599-602

13. Sharrock NE, Cazan MG, Hargett MJ, Williams-Russo P, Wilson PD Jr (1995) Changes in mortality after total hip and knee arthroplasty over a ten-year period. Anesth Analg 80:242-248

14. Frostick SP (2000) Death after joint replacement. Haemostasis 30 [Suppl 2]:84-87; discussion pp 82-83

15. Mantilla CB, Horlocker TT, Schroeder DR, Berry DJ, Brown DL (2002) Frequency of myocardial infarction, pulmonary embolism, deep venous thrombosis, and death following primary hip or knee arthroplasty. Anes- thesiology 96:1140-1146

16. Callahan CM, Drake BG, Heck DA, Dittus RS (1995) Patient outcomes following unicompartmental or bicompartmental knee arthroplasty. A meta-analysis. J Arthroplasty 10:141-150

17. Gill GS, Mills D, Joshi AB (2003) Mortality following primary total knee arthroplasty. J Bone Joint Surg [Am] 85:432-435

18. Colwell CW (2004) Low molecular weight heparins. American Academy of Orthopedic Surgeons Annual Meeting, San Francisco, March 10-14

Chapter 60 · Patient Selection and Counseling – C. Mahoney, K. L. Garvin ³⁸³

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