Full-Thickness Cartilage Defects More Predictive of Future TKA than Joint-Space Narrowing
Many older patients present to orthopaedic surgeons with clinical knee pain suggestive of osteoarthritis (OA) but with little or no radiographic evidence of disease. And a substantial proportion of those patients do not respond adequately to the recommended, first-line nonsurgical treatment approaches to knee OA. A prognostic study by Everhart et al. in the January 2, 2019 issue of The Journal of Bone & Joint Surgery helps explain why that might be.
The authors evaluated baseline knee radiographs and MRIs from >1,300 older adults (mean age of 61 years) who were enrolled in the Osteoarthritis Initiative, a multicenter observational cohort study with a median of 9 years of follow-up data. They sought to determine independent risk factors for progression to total knee arthroplasty (TKA) among this cohort, all of whom showed Kellgren-Lawrence grade 0 to 3 OA on knee radiographs. MRIs taken at baseline revealed that 38% of those patients had a full-thickness knee-cartilage defect. After the authors adjusted for various confounders (including age, weight, and symptom severity), they found that regardless of radiographic grade, the presence of a full-thickness cartilage defect was a strong independent risk factor for subsequent TKA. Moreover, patients with a defect ≥2 cm2 had twice the risk of arthroplasty compared with patients with defects <2 cm2.
According to the authors, the findings highlight the “greater importance of full-thickness cartilage loss over radiographic OA grade as a determinant of OA severity, specifically regarding the risk of future knee arthroplasty in older adults.” In his commentary on this study, Drew A. Lansdown, MD emphasizes that Everhart et al. “do not advocate for the routine use of MRI in the diagnosis of knee osteoarthritis,” but he says the findings “do suggest that early MRI may have a diagnostic role for patients who are not responding as expected to nonoperative measures.” Noting that the patients in this cohort would probably not be ideal candidates for current cartilage-restoration procedures, Dr. Lansdown encourages further research focused on identifying “patient-specific factors that can match patients with the treatment…that will provide the greatest likelihood of symptom relief and functional improvement.”
After Bunion Surgery, Immediate X-rays Predict Recurrence Risk
Recurrence rates after surgical treatment for hallux valgus (bunion) range from 4% to 25%. Findings from a study by Park and Lee in the July 19, 2017 edition of The Journal of Bone & Joint Surgery suggest that non-weight-bearing radiographs taken immediately after surgery can provide a good estimate of the risk of recurrence.
The study analyzed proximal chevron osteotomies performed on 117 feet. At an average follow-up of two years, the hallux valgus recurrence rate was 17%. (Recurrence was defined as a hallux valgus angle [HVA] of ≥20°.)
Bunions were 28 times more likely to recur when the postoperative HVA was ≥8° than when the HVA was <8°. The HVA continued to widen over time in patients with recurrent bunions, but stabilized at six months in those without recurrence. An immediate postoperative sesamoid position of grade 4 or greater was also significantly associated with recurrence.
If future studies confirm their results, the authors believe that such data could be used “to suggest intraoperative guidelines for satisfactory correction of radiographic parameters,” and thus help surgeons minimize the risk of hallux valgus recurrence. Commentator Jakup Midjord, MD concurs, noting that non-weight-bearing radiographs can be “closely related to intraoperative radiographs, so we can modify correction as needed in the operating room.”
JBJS Editor’s Choice—Nonunions of Foot/Ankle Fusions Matter
In the December 7, 2016 issue of JBJS, Krause et al. analyze data from a 2013 industry-sponsored RCT to investigate correlations between nonunions of hindfoot/ankle fusions indicated by early postoperative computed tomography (CT) and subsequent functional outcomes. Whether nonunion was assessed by independent readings of those CT scans at 24 weeks or by surgeon composite assessments at 52 weeks, patients with failed healing had lower AOFAS, SF-12, and Foot Function Index scores than those who showed osseous union.
This study suggests that a CT should be obtained from patients who are at least 6 months out from a surgical fusion and are not progressing in terms of activity-related pain and function. Depending on the specific CT findings, a repeat attempt at bone grafting, with the possible addition of bone-graft substitute and/or possible modification of internal fixation, may be warranted to forestall later clinical problems.
Krause et al. imply that trusting plain radiographs that show no indication of fusion failure is not acceptable when patient pain and function do not improve in a timely fashion. Conversely, they conclude that their findings do not support “the concept of an asymptomatic nonunion (i.e., imaging indicating nonunion but the patient doing well),” because nonunions identified early by CT eventually resulted in worse clinical outcomes. The authors also noted that obesity, smoking, and not working increased the risk of nonunion, corroborating findings from earlier studies.
While advanced imaging such as CT is not necessary in foot/ankle fusion patients who are improving in terms of function, pain, and swelling , this study stresses the importance of achieving union following these fusion procedures.
Marc Swiontkowski, MD
JBJS Editor-in-Chief
X-rays Miss Many Cases of Hip Osteoarthritis
It’s a good thing orthopaedists don’t rely solely on X-rays to diagnose hip osteoarthritis (OA), because an analysis of data from two large cohort studies casts doubt about the utility of radiographs in diagnosing hip OA in older patients.
Using pain localized to the groin or anterior hip or provoked by internal rotation as the clinical standard for diagnosing hip OA, the researchers compared participants’ reports of such pain with radiographic evidence. In the first cohort study (n=946), only 15.6% of hips in patients reporting frequent hip pain showed radiographic evidence of osteoarthritis. In the second study (n=4366), only 9.1% of hips in patients with frequent pain showed radiographic evidence of hip OA. Conversely, pain was not present in many hips with radiographic evidence of osteoarthritis.
These findings strongly indicate that many cases of hip arthritis would be missed if clinicians relied solely, or even largely, on radiographs. The findings also suggest that overdiagnosis of osteoarthritis would be likely if doctors relied on radiographs rather than examining patients and obtaining an appropriate history. The authors conclude that “health professionals should continue to evaluate and treat patients with hip pain suggestive of osteoarthritis despite negative radiographic findings.” This study is also a good reminder for physicians to treat patients, not imaging studies.
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