The Academy Board of Directors in December approved release of two new sets of Appropriate Use Criteria (AUC), covering Carpal Tunnel Syndrome (CTS) and Surgical Management of Osteoarthritis of the Knee (SMOAK).

As with previously issued AUC, these new app-based resources (www.aaos.org/auc) provide clinicians with an algorithm-style tool for choosing management pathways for patients with these conditions. They provide recommendations for treatment scenarios based on the reviews of evidence and conclusions issued in the Clinical Practice Guidelines (CPGs) for each of these topics.

Carpal tunnel: Charting the hierarchy
The AUC covering CTS comprises 135 diagnostic scenarios to help a clinician decide whether the patient has CTS and, if so, what the appropriate treatment would be. The full spectrum of treatment is covered—from nonsurgical, including splint, to steroid injection, to surgical release.

"Carpal tunnel is a complex diagnosis," said Robert H. Quinn, MD, AUC Section Leader, Committee on Evidence-Based Quality and Value. "CTS has seen significant variations in approach, diagnosis, and treatment, and the AUC succinctly directs the orthopaedic surgeon toward a fairly narrow, evidence-based decision-making and treatment pathway."

The avenues involved in this AUC "may be a bit more complex than some others," said Dr. Quinn, "because there exists a more involved hierarchy on both treatment and management directions. Often the treatment scenarios in other AUCs are simpler—such as for knee arthritis in the young person in the SMOAK AUC."

He explained that the AUC yields treatment recommendations based on a hierarchy of several diagnostic criteria.

"A higher probability of CTS as demonstrated by signs, symptoms, and the results of electrodiagnostic testing indicates increasing appropriateness for specific treatments, including invasive treatments such as steroid injection or carpal tunnel release (Fig. 1)," Dr. Quinn said.

"The weaker the evidence that CTS is present, as seen in electrodiagnostic testing, or the less severe the symptoms, the more the AUC is weighted toward alternative diagnoses," he continued. "In these scenarios, recommendations may include investigating further with electrodiagnostic testing, treating conservatively, and being less likely to use invasive treatment such as injection or release."

For example, in a patient with moderate likelihood of CTS based on clinical examination; electrodiagnostic testing not consistent with CTS; moderate clinical severity (pain/sensory disturbances, tingling, frequent activity-related symptoms, and/or difficulty with fine motor coordination); and positive response to nonsurgical treatment and subsequent recurrence of symptoms, the AUC tool would issue the following recommendations, as shown in Fig. 2.

• Appropriate: Investigate alternative diagnosis; administer steroid injection
• May Be Appropriate: Oral steroids or ketoprofen phonophoresis; splint (nonoperative treatment); carpal tunnel release (nonoperative treatment)
• Rarely Appropriate: Investigate further: electrodiagnostic study

Dr. Quinn explained that the panel creating the AUC "looked at probability of whether an electrodiagnostic test was performed and if it supported CTS, how severe the symptoms were, and whether or not they responded to surgical treatment. If you take all those considerations together, the more support you have for CTS. The more severe it is, and the more it has failed to respond to conservative treatment, the more likely we are to recommend surgery at the end of the continuum."

SMOAK: A matter of age
The AUC on SMOAK, Dr. Quinn explained, focuses on three possible surgical modalities for knee arthritis:

• Total knee arthroplasty (TKA)
• Unicompartmental knee arthroplasty (medial or lateral tibiofemoral joint, not patellofemoral)
• Realignment osteotomy (varus- or valgus-producing femoral or tibial osteotomy)

The tool covers 864 scenarios that take into account patient pain and function; range of motion/extension-flexion; functional instability; pattern of arthritic involvement (medial tibiofemoral, lateral tibiofemoral, or patellofemoral); joint space seen on imaging; limb alignment; mechanical symptoms (compatible with meniscal tear or loose body); and age.

The most important parameter for treatment recommendations is age, according to Dr. Quinn.

"When you look at the different scenarios, as age goes up, the recommendation for TKA tends to become more global. As age goes down, unicomparmental knee arthroplasty and realignment osteotomy are potentially more attractive in patients with disease limited to one compartment or in patients who have varus or valgus deformity."

A primary issue is that of revision, he said. "The younger the patient is, presumably the longer he or she will live with the treatment—and therefore the higher likelihood that the implant will be revised. We want to preserve as much normal anatomy for as long as we can, at the potential cost of either a shorter time period to revision—unicompartmental—or a potentially more difficult revision if it is an osteotomy.

"TKA will last the longest and address symptoms for the longest period," he continued, "but revision of TKA comes at a higher cost of losing more bony anatomy. The unicompartmental arthroplasty preserves more normal anatomy at the cost of higher probability of a need for revision to TKA down the road. Realignment osteotomy is a fairly major procedure that can buy time in a younger patient and preserve anatomy, but it can make for a more complicated TKA when the time comes."

Both AUC are now available on the AUC section of the OrthoGuidelines app via desktop at www.orthoguidelines.org/auc; for mobile devices, the native OrthoGuidelines app can be downloaded via the iOS or Google Play stores.

Terry Stanton is the senior science writer for AAOS Now. He can be reached at tstanton@aaos.org