Exercise for patellar tendinopathy

Patellar tendinopathy is a prevalent condition that commonly affects the tendon's origin, causing pain at the front of the knee. The main treatment for patellar tendinopathy involves different types of exercise (e.g. strengthening and stretching). The most common method of strengthening exercise is eccentric (lengthening) muscle loading. Strengthening exercises can be land-based or water-based, weight-bearing or non-weight-bearing, or both. Other treatments include surgery and glucocorticoid injections.

To evaluate the benefits and harms of exercise for the treatment of patellar tendinopathy.

We searched the Cochrane Central Register of Controlled Trials (CENTRAL), MEDLINE, Embase, and two trials registers to 5 September 2023, with no restrictions by language.

We included randomized controlled trials of strengthening exercise interventions compared to placebo or sham intervention; no treatment, usual care, or minimal intervention; or other active intervention. Strengthening exercises include concentric, eccentric, eccentric-concentric, and isometric exercises designed to enhance the strength and power of muscles.

Two review authors independently selected studies for inclusion, extracted data, and assessed risk of bias and certainty of evidence using GRADE. Major outcomes included pain, function, participant-reported global assessment of treatment success, quality of life, return to sport, proportion of participants with adverse events, and proportion of participant withdrawals.

We included seven trials (211 participants with chronic patellar tendinopathy) comparing strengthening exercises with no treatment (3 trials, 93 participants), glucocorticoid injection (1 trial, 38 participants), surgery (1 trial, 40 participants), stretching exercise (1 trial, 15 participants), or pulsed ultrasound and transverse friction (1 trial, 30 participants). All trials included athletes (88% males, mean age 26 years) with a mean duration of symptoms of 41.6 months. Most trials were susceptible to bias, particularly selection bias/random sequence (57.1%), selection bias/allocation concealment (42.8%), detection bias (28.5%), attrition bias (71.4%), and selective reporting biases (28.5%). Given the nature of the intervention, neither participants nor investigators were blinded to group allocation in any trials (performance bias). We did not find any studies that compared exercise with placebo or sham intervention. Strengthening exercise versus no treatment We are very uncertain whether strengthening exercise reduces pain compared to no treatment. Mean pain with no treatment was 62.00 points on a 0 to 100 scale (0 = no pain) compared to 27.06 points with exercise (mean difference (MD) 34.94 points better, 95% confidence interval (CI) 20.94 better to 48.94 better; 1 study, 39 participants; very low-certainty evidence (downgraded twice for imprecision and once for bias)). Strengthening exercise may make little or no difference to function compared to no treatment at the end of treatment. Mean function with no treatment was 65.00 points on a 0 to 100 scale (100 = best function) compared to 72.04 points with exercise (MD 7.04 points better, 95% CI 6.94 points worse to 21.02 points better; 2 studies, 95 participants; low-certainty evidence (downgraded once for imprecision and once for bias)). The studies reported none of the other outcomes. Strengthening exercise versus glucocorticoid injection Strengthening exercise may make little or no difference to pain compared to glucocorticoid injection at the end of treatment. Mean pain with glucocorticoid injection was 18.00 points on a 0 to 100 scale (0 = no pain) compared to 24.04 points with exercise (MD 6.04 points worse, 95% CI 8.19 better to 20.26 better; 1 trial, 38 participants; low-certainty evidence (downgraded twice for imprecision)). Strengthening exercise may make little or no difference to function compared to glucocorticoid injection at the end of treatment. Mean function with no treatment was 82.00 points on a 0 to 100 scale (100 = best function) compared to 76.25 points with exercise (MD 5.75 points worse, 95% CI 17.41 worse to 5.93 better; 1 trial, 38 participants; low-certainty evidence (downgraded twice for imprecision)). The trial reported none of the other outcomes. Strengthening exercise versus surgery We are very uncertain whether strengthening exercise reduces pain compared to surgery at 12-month follow-up. Mean pain with surgery was 13.00 points on a 0 to 100 scale (0 = no pain) compared to 17.00 points with exercise (MD 4.00 points worse, 95% CI 4.06 better to 12.06 worse; 1 trial, 40 participants; very low-certainty evidence). We are very uncertain whether strengthening exercise improves function compared to surgery. Mean function in the surgery group at the end of treatment was 45.10 points on a 0 to 100 scale (100 = best function) compared to 52.4 points in the exercise group (MD 7.30 points better, 95% CI 5.02 worse to 19.62 better; 1 trial, 40 participants; very low-certainty evidence (downgraded once for bias and twice for serious imprecision)). Strengthening exercise may make little or no difference to treatment success compared to surgery at the end of treatment. The mean global assessment of treatment success with surgery was 0.2 points on a -5 to +5 scale (+5 maximum was improvement) compared to 1.76 points with exercise (MD 1.56 points better, 95% CI 0.52 worse to 3.64 better; 1 trial, 40 participants; low-certainty evidence (downgraded once for bias and once for imprecision)). Strengthening exercise may make little or no difference to the rate of participants who returned fully or partially to sport when compared to surgery at 12-month follow-up. The return to sport rate with surgery was 86% compared to 85% with exercise (risk ratio 1.02, 95% CI 0.78 to 1.34; 1 trial, 40 participants; low-certainty evidence (downgraded once for bias and once for imprecision)). The trial reported none of the other outcomes.

We are very uncertain whether strengthening exercise reduces pain compared to no treatment. Strengthening exercise may make little or no difference to function compared to no treatment and to function or pain compared to glucocorticoid injection. Compared to surgery, we are very uncertain whether strengthening exercise reduces pain or improves function, and it may make little or no difference to treatment success and the proportion of athletes returning to sport. No trials measured adverse events. All trials analyzed in this review included participants who were athletes, limiting the findings to athletes rather than the general public.