Patient profile scrutiny can help surgeons to predict results after TKA

Tourniquet use for patients with diabetes may cause postischemic neuropathy, expert warns.

Issue: February 2007

Choosing the right patient for a procedure can be an integral part of obtaining good outcomes after surgery.

At the 23rd Annual Current Concepts in Joint Replacement Winter 2006 Meeting, Kenneth A. Krackow, MD, discussed how surgeons can identify the best and worst candidates for total knee arthroplasty (TKA).

"I put to you that your easiest case is the optimistic personality who has significant pathology, no deformity, good range of motion, is not obese, not on workman's compensation, does not have diabetes or circulatory problems, has had no prior surgery [and] certainly no history of infection," Krackow said during his presentation. "Well, we just do notsee too many of those patients, I'm sorry."

When profiling patients for successful total knee replacement, Krackow said that surgeons should consider the following:

why surgery is offered to the patient;
the factors that affect the difficulty of performing the procedure; and
patient characteristics that may influence postoperative outcomes.

Patient profiles

Before offering TKA, surgeons should ensure that the patient has sufficient pathology and determine whether the pain is osteoarthritic or neuropathic in nature.

"Are there any special socioeconomic factors like changes in retirement or even medical benefits that would be impacted by the timing [of the surgery]?" Krackow said. Physicians should also check that their patients' postoperative goals are realistic, he said.

Patient profiles that include deformity, skin problems, prior surgery, decreased range of motion or obesity can increase surgical difficulty. Krackow noted that surgeons should be wary of using tourniquets on patients with diabetes.

"I've been suspicious of unusual pain in diabetics for years," he said. "And we do have some documentation in the literature now with ischemic neuropathy as the cause of this pain,"

Surgical candidates with poor cardiopulmonary function may also be problematic, he said.

While surgeons have shown caution in treating patients with peripheral vascular disease, "just bad vessel disease may be a consideration," Krackow said. Other factors that may increase surgical complexity include the use of antibiotic cement, sham incision tests and preoperative biopsy.

Workers' comp, obesity

Patient characteristics such as workers' compensation status, obesity and diabetes can also influence surgical outcomes. Krackow cited a matched-cohort study by Michael Mont, MD, which found that only 29% of workers' compensation patients had good or excellent results after TKA compared to 88% in the comparison group. Mont also found that the non-workers' compensation group also had better postop activity and more had prior successful surgeries.

A similar study by Khaled Saleh, MD, showed that only five of 20 workers' compensation patients returned to work postoperatively. "Even more interesting, the objective measures of range of motion and so forth, were basically equal," Krackow said.

He also noted that Canadian research found more outpatient visits and pain and less range of motion in workers' compensation patients.

While researchers have often seen a correlation between surgical results and workers' compensation, Krackow said that there is conflicting data regarding obesity and surgical outcomes. While some studies show no difference in the revision rates between obese and nonobese patients, research by Michael Mount, MD, and David Hungerford, MD, revealed higher revision rates and worse knee scores in obese patients.

Krackow also cited research by Robert Bourne, MD, who found that the odds of undergoing a knee replacement increase 1.5 times for patients with a body mass index between 25 and 30. Yet, a 370-case study by Ahmet found that obesity had no effect on outcomes.

"So, I think it's hard to figure out this one," Krackow said.

Researchers have also found various problems in diabetic patients following TKA, including urinary tract problems, wound infections and neuropathy.

"At Mayo, the medical and surgical complications in general surgery were much higher in the diabetic patients and, interestingly, they saw some radiolucent line issues," Krackow said.

Surgeons have also reported instability in patients with rheumatoid arthritis.

"And there's a lot of debate about whether or not PS [posterior cruciate-substituting] knees should be used," Krackow said. "Nonetheless, the rheumatoids have a good survivorship."

Researchers have also found superior results in patients who have not undergone previous surgery.

"I've never read a paper were folks without prior surgery didn't do better," Krackow said. "Post-traumatic issues are there and present some structural and planning issues."

For more information:
Krackow K. Patient profiling: Your next successful TKA. #82. Presented at the 23rd Annual Current Concepts in Joint Replacement Winter 2006 Meeting. Dec. 13-16, 2006. Orlando, Fla.
Kenneth A. Krackow, MD, clinical director of orthopedics, Buffalo General Hospital, 100 High Street Suite B-276, Buffalo, NY 14203-1126; 716-859-1256; kkrackow@buffalo.edu. He has received consulting, teaching and speaking funds from Stryker.