Patellofemoral grind associated with subsequent cartilage loss and need for knee replacement

A simple clinical exam may provide physicians with an inexpensive way to identify patients at higher risk for accelerated cartilage volume loss and total knee replacement who should be targeted for surveillance and management, study authors said.

Patellofemoral grind, but not joint-line tenderness, may represent a clinical marker associated with accelerated cartilage volume loss over four years and increased risk of total knee replacement within six years, a study found.

The study included 4,353 participants in the National Institutes of Health Osteoarthritis Initiative, a publicly available multicenter observational cohort study of knee osteoarthritis. Joint-line tenderness was assessed by palpating the medial and lateral tibiofemoral joint line with the participant's knee bent 90 degrees. Patellofemoral grind was assessed by providing distal force at the superior border of the patella as the participant contracted the quadriceps. Pain was considered a positive sign and was recorded for the medial joint line, lateral joint line, and patellofemoral joint.

For joint-line tenderness and patellofemoral grind, patterns were defined as no (none at baseline and one year), fluctuating (present at either time point), and persistent (present at both time points). Cartilage volume loss and worsening of radiographic osteoarthritis over four years were assessed using MRI and X-ay, as well as total knee replacement rates in six years. Results were published April 22 by Arthritis Care & Research.

Among the participants, 2,236 (51.4%) had radiographic osteoarthritis, 1,094 (35.0%) had joint line tenderness, and 684 (15.8%) had patellofemoral grind at baseline. Annual rate of cartilage volume loss was higher in participants with patellofemoral grind at baseline than in those without (1.08% vs. 0.96%; P=0.02]. Cartilage volume loss was also greater in participants with fluctuating patellofemoral grind (1.12%; P<0.001) and persistent patellofemoral grind (1.30%; P<0.001) than in those with no patellofemoral grind (0.90%).

Patterns of joint-line tenderness were not significantly associated with joint outcomes, but participants with persistent patellofemoral grind had increased risk of total knee replacement (odds ratio, 2.10; 95% CI, 1.30 to 3.38; P=0.002) versus those without patellofemoral grind.

This simple clinical examination may provide clinicians with an inexpensive way to identify those at higher risk of disease progression who should be targeted for surveillance and management, the authors noted.

“Clinicians are faced with increasing numbers of patients with knee [osteoarthritis] due to the escalating incidence and prevalence of the disease globally. Targeting patients at risk of disease progression for surveillance and management will facilitate more efficient utilisation of health care resources,” they wrote.