Knee osteoarthritis

Objective: To assess the efficacy and safety of various exercise modalities as therapeutic interventions for managing knee osteoarthritis.

Design: Systematic review with network meta-analysis.

Data sources: PubMed, Embase, Cochrane Library, Web of Science, CINAHL, PsycINFO, AMED, PEDro, Scopus, ClinicalTrials.gov, ICTRP, and ClinicalTrialsRegister.eu from database inception to August 2024.

Eligibility criteria for selecting studies: Randomised controlled trials comparing different exercise modalities, including aerobic exercise, flexibility exercise, mind-body exercise, neuromotor exercise, strengthening exercise, mixed exercise, and control group for patients with knee osteoarthritis.

Main outcome measures: Primary outcomes included pain, function, gait performance, and quality of life, assessed at short term (four weeks), mid-term (12 weeks), and long term (24 weeks) follow-up. When exact time points were unavailable, data from adjacent time windows were used.

Results: 217 randomised controlled trials involving 15 684 participants were included. Moderate certainty evidence showed that, compared with the control group, aerobic exercise probably results in large improvements in pain at short term (standardised mean difference -1.10, 95% confidence interval -1.68 to -0.52) and mid-term follow-up (-1.19, -1.59 to -0.79), function at mid-term (1.78, 1.05 to 2.51), gait performance at mid-term (0.85, 0.55 to 1.14), and quality of life at short term (1.53, 0.47 to 2.59). Mind-body exercise probably results in a large increase in function at short term follow-up (0.88, 0.03 to 1.73; moderate certainty), while neuromotor exercise probably results in a large increase in gait performance at short term follow-up (1.04, 0.51 to 1.57; moderate certainty). Strengthening (0.86, 0.53 to 1.18) and mixed exercise (1.07, 0.68 to 1.46) probably result in a large increase in function at mid-term follow-up, all with moderate certainty evidence. Regarding long term follow-up, flexibility exercise may result in a large reduction in pain (-0.99, -1.63 to -0.36; low certainty); aerobic exercise may result in a large increase in function (0.87, 0.02 to 1.72, low certainty); and mixed exercise may increase function (0.56, 0.26 to 0.86; low certainty) and probably increases gait performance (0.57, 0.21 to 0.92, moderate certainty). Overall, aerobic exercise consistently showed the highest probability of being the best treatment, as reflected by surface under the cumulative ranking curve values (mean 0.72) across outcomes. The safety outcome was reported in a small proportion of studies (40 studies, 18%), and no clear differences were observed between exercise interventions and control.

Conclusions: In patients with knee osteoarthritis, aerobic exercise is likely the most beneficial exercise modality for improving pain, function, gait performance, and quality of life, with moderate certainty.

Systematic review registration: PROSPERO CRD42023469762.

Importance: Approximately 5% of all primary care visits in adults are related to knee pain. Osteoarthritis (OA), patellofemoral pain, and meniscal tears are among the most common causes of knee pain.

Observations: Knee OA, affecting an estimated 654 million people worldwide, is the most likely diagnosis of knee pain in patients aged 45 years or older who present with activity-related knee joint pain with no or less than 30 minutes of morning stiffness (95% sensitivity; 69% specificity). Patellofemoral pain typically affects people younger than 40 years who are physically active and has a lifetime prevalence of approximately 25%. The presence of anterior knee pain during a squat is approximately 91% sensitive and 50% specific for patellofemoral pain. Meniscal tears affect an estimated 12% of the adult population and can occur following acute trauma (eg, twisting injury) in people younger than 40 years. Alternatively, a meniscal tear may be a degenerative condition present in patients with knee OA who are aged 40 years or older. The McMurray test, consisting of concurrent knee rotation (internal or external to test lateral or medial meniscus, respectively) and extension (61% sensitivity; 84% specificity), and joint line tenderness (83% sensitivity; 83% specificity) assist diagnosis of meniscal tears. Radiographic imaging of all patients with possible knee OA is not recommended. First-line management of OA comprises exercise therapy, weight loss (if overweight), education, and self-management programs to empower patients to better manage their condition. Surgical referral for knee joint replacement can be considered for patients with end-stage OA (ie, no or minimal joint space with inability to cope with pain) after using all appropriate conservative options. For patellofemoral pain, hip and knee strengthening exercises in combination with foot orthoses or patellar taping are recommended, with no indication for surgery. Conservative management (exercise therapy for 4-6 weeks) is also appropriate for most meniscal tears. For severe traumatic (eg, bucket-handle) tears, consisting of displaced meniscal tissue, surgery is likely required. For degenerative meniscal tears, exercise therapy is first-line treatment; surgery is not indicated even in the presence of mechanical symptoms (eg, locking, catching).

Conclusions and Relevance: Knee OA, patellofemoral pain, and meniscal tears are common causes of knee pain, can be diagnosed clinically, and can be associated with significant disability. First-line treatment for each condition consists of conservative management, with a focus on exercise, education, and self-management.

Importance: Physical therapy and glucocorticoid injections are initial treatment options for knee osteoarthritis, but available data indicate that most patients receive one or the other, suggesting they may be competing interventions. The initial cost difference for treatment can be substantial, with physical therapy often being more expensive at the outset, and cost-effectiveness analysis can aid patients and clinicians in making decisions.

Objective: To investigate the incremental cost-effectiveness between physical therapy and intra-articular glucocorticoid injection as initial treatment strategies for knee osteoarthritis.

Design, setting, and participants: This economic evaluation is a secondary analysis of a randomized clinical trial performed from October 1, 2012, to May 4, 2017. Health economists were blinded to study outcomes and treatment allocation. A randomized sample of patients seen in primary care and physical therapy clinics with a radiographically confirmed diagnosis of knee osteoarthritis were evaluated from the clinical trial with 96.2% follow-up at 1 year.

Interventions: Physical therapy or glucocorticoid injection.

Main outcomes and measures: The main outcome was incremental cost-effectiveness between 2 alternative treatments. Acceptability curves of bootstrapped incremental cost-effectiveness ratios (ICERs) were used to identify the proportion of ICERs under the specific willingness-to-pay level ($50 000-$100 000). Health care system costs (total and knee related) and health-related quality-of-life based on quality-adjusted life-years (QALYs) were obtained.

Results: A total of 156 participants (mean [SD] age, 56.1 [8.7] years; 81 [51.9%] male) were randomized 1:1 and followed up for 1 year. Mean (SD) 1-year knee-related medical costs were $2113 ($4224) in the glucocorticoid injection group and $2131 ($1015) in the physical therapy group. The mean difference in QALY significantly favored physical therapy at 1 year (0.076; 95% CI, 0.02-0.126; P = .003). Physical therapy was the more cost-effective intervention, with an ICER of $8103 for knee-related medical costs, with a 99.2% probability that results fall below the willingness-to-pay threshold of $100 000.

Conclusions and relevance: A course of physical therapy was cost-effective compared with a course of glucocorticoid injections for patients with knee osteoarthritis. These results suggest that, although the initial cost of delivering physical therapy may be higher than an initial course of glucocorticoid injections, 1-year total knee-related costs are equivalent, and greater improvement in QALYs may justify the initial higher costs.