Patellofemoral cartilage degeneration may progress after high tibial osteotomy
Investigators of a recently published study found high tibial osteotomies may progress patellofemoral cartilage degeneration and should be selected with careful consideration for osteoarthritic status and correction angles.
Researchers from the department of orthopedic surgery at Kyung Hee University in Seoul, South Korea, retrospectively analyzed data for 54 closed-wedge high tibial osteotomies (CWHTO) and 50 open-wedge high tibial osteotomies (OWHTO) performed by two senior surgeons from a single institution between 2013 and 2017.
According to the study, researchers arthroscopically evaluated each knee using the International Cartilage Repair Society grading system. Patellofemoral cartilage degeneration was determined by a at least one ICRS grade progression on the patella or femoral trochlea. Clinical evaluation consisted of WOMAC, range of motion and anterior knee pain scale, while radiographic evaluation consisted of mechanical axis change (or correction angle), tibial posterior slope angle and modified Blackburne-Peel ratio.
While WOMAC, range of motion and anterior knee pain scale results improved postoperatively in both groups, researchers noted a change in ICRS grading of the patellofemoral cartilage, according to the study. At second-look arthroscopy, the percentage of knees with patellofemoral cartilage degeneration was 29.6% (16 knees) in the CWHTO group and 44% (22 knees) in the OWHTO group.
After performing logistic regression analysis, researchers found correction angle as factor that affects patellofemoral cartilage degeneration.
“A correction angle [of at least 10°] was associated with patellofemoral cartilage degeneration after both CWHTO and OWHTO,” the researchers wrote in the study.
“Patellofemoral cartilage degeneration progressed after CWHTO and OWHTO with large alignment correction,” they concluded. “High tibial osteotomy should be selected with careful consideration of the osteoarthritic status of the patellofemoral joint and required correction angle, regardless of applying a closed- or open-wedge technique,” they wrote.
Perspective
Back to Top
There is concern regarding patellofemoral cartilage degeneration after high tibial osteotomy (HTO). This is multifactorial but involves changes in patellofemoral joint pressure or congruency associated with HTO. This has been recognized when patella height is lowered following opening-wedge HTO (OWHTO). These detrimental effects may be mitigated by closing-wedge HTO (CWHTO) techniques.
Sang Jun Song, MD, PhD, and colleagues compared patellofemoral cartilage degeneration after OWHTO or CWHTO in matched cohorts. While coronal plane corrections were similar, patella height was lower in the OWHTO group. However, both groups had progression of patellofemoral cartilage degeneration (29.6% CWHTO vs. 44% OWHTO, P=.156) and large corrections (approximately 10°) increased the odds of degenerative changes regardless of technique.
Strengths include matched cohorts, standardized techniques and the use of second-look arthroscopy. Weaknesses include retrospective design, lack of control group or randomization, and small sample size with short-term follow-up. Care must be taken not to generalize findings from mostly female Asian medial arthritics with all patients undergoing HTO.
Nonetheless, the study raises a “red flag” regarding progression of patellofemoral disease following large correction HTO. Surgeons must carefully evaluate patellofemoral alignment preoperatively and consider methods to optimize patellofemoral tracking in their comprehensive surgical plan.
Collapse