Comparison of instrument-assisted soft tissue mobilization and proprioceptive neuromuscular stretching on hamstring flexibility in patients with knee osteoarthritis.

Tight hamstrings are common in people with knee osteoarthritis, and the tightness can add extra strain on the joint, limit movement, and encourage compensatory patterns that may worsen symptoms over time. This trial compared two manual therapy approaches aimed at improving hamstring flexibility, one using a tool-assisted technique called instrument-assisted soft tissue mobilization and the other using a stretching method called proprioceptive neuromuscular stretching, in 60 people with knee osteoarthritis over six weeks of supervised sessions. Both approaches were followed by improvements in hamstring flexibility, pain, and general health status measures, but the instrument-assisted technique showed greater improvement than the stretching approach on all three measures. The finding is interesting because it suggests manual tool-based techniques might offer an edge over a well-established stretching method, though this comes from a single moderately sized trial, so the result should be read as an initial comparison rather than settled evidence.

If you have knee osteoarthritis, you may have noticed that your hamstrings, the muscles at the back of your thigh, feel tight. Tight hamstrings can add strain to the knee and limit how far it can move, which may make everyday activities like walking or getting up from a chair harder.

Researchers wanted to know whether a hands-on technique using a specialized tool, called instrument-assisted soft tissue mobilization, or a common stretching method, called proprioceptive neuromuscular stretching, would help loosen these muscles and ease symptoms. In this six-week trial with 60 participants split into two groups, both treatments led to improvements in flexibility, pain, and overall health status related to knee osteoarthritis. The tool-based technique showed somewhat larger improvements than the stretching method across all three measures.

This is a single trial of modest size, so while the results are encouraging for both approaches, they represent an early comparison rather than a definitive answer about which method works better long term or in broader populations.

This is a summary of research, not medical advice. Talk to your own healthcare provider about anything affecting your care.

This randomized controlled trial (NCT05110326) compared instrument-assisted soft tissue mobilization (IASTM) against proprioceptive neuromuscular (PNF) stretching for hamstring flexibility in patients with knee osteoarthritis, using 60 participants divided into two groups of 30 receiving three 30-minute sessions weekly for six weeks. Outcomes included the visual analog scale for pain, the active knee extension test for hamstring flexibility, and the WOMAC index for disease-related health status, assessed via a group by time interaction analysis. Both groups showed statistically significant within-group improvements across all three outcomes after six weeks (p < 0.001), and the between-group comparison favored IASTM over PNF stretching, also reaching statistical significance (p < 0.001) for flexibility, pain, and WOMAC scores.

This establishes a direct head-to-head comparison rather than separate comparisons against a control, which strengthens the interpretability of the group difference reported. Clinicians should weigh this against the trial's scale: a single study of 60 participants with a six-week follow-up does not establish long-term durability, and the abstract gives no information on blinding, dropout, or adverse events, all of which affect confidence in the magnitude of the reported advantage. The findings indicate a statistically significant difference favoring IASTM in this specific protocol, without yet establishing broader clinical superiority.