To compare the effectiveness of shockwave therapy with a traditional conservative treatment program for chronic proximal hamstring tendinopathy in professional athletes.
Randomized controlled trial, with 12 months of follow-up. Sample size was calculated with 80% power to show a difference of 3 points on a visual analog scale (VAS, 0-10 points; “no pain” to “worst pain”) at P ≤ 0.05, adjusted for multiple comparisons.
Tertiary imaging and rehabilitation center in Sulmona, Italy, with enrollment between February 2004 and September 2006.
Patients with chronic proximal hamstring tendinopathy diagnosed by the presence of ≥2 of 3 positive clinical tests (the Puranen-Orava test, the fast hamstring-stretch test, or the hamstring strength test), a pain score of ≥4 cm on the VAS, and abnormalities in the proximal hamstring tendon on magnetic resonance imaging using a grading system devised for Achilles tendinopathy (Khan system) were eligible. Exclusion criteria were other clinical syndromes and conditions, including hamstring muscle tears or pain of presumed lumbar spine origin, age ≥18 years, and any treatment in the previous 4 weeks. Of 52 patients assessed for eligibility, 27 men and 13 women met criteria.
The 20 patients in the shockwave therapy group were assigned to 4 sessions, once per week, of 2500 shocks per session at an energy flux density of 0.18 mJ/mm2 directed to the area of maximal tenderness. Weight bearing and unrestricted range of motion were allowed immediately. No cointerventions except intermittent icing of the treated area were permitted. Patients were instructed to avoid activities that increased their symptoms. The patients in the traditional conservative treatment group were instructed to rest and to take 600-mg ibuprofen twice daily for the first week. For the first 2 weeks, they were assigned to physiotherapy consisting of daily ultrasound and transverse friction massage 3 times per week. This was followed by 3 weeks of stretching and strengthening work, including isotonic exercises, lunges, and jumps, performed 3 times per week.
Main Outcome Measures
The primary outcome measures 3 months after treatment were a mean difference of ≥3 cm between groups in the reduction in pain scores on the self-rated VAS and a mean difference in improvement between groups on the Nirschl phase rating scale (NPRS, phases 1-7, least pain and activity limitation to constant pain at rest). Patients who had surgery (15%) were not evaluated subsequently.
After 3 months, the mean reduction in pain scores was 5.0 cm for the shockwave therapy group compared with 0.2 cm for the traditional conservative treatment group (95% confidence interval [CI] for the difference of 4.7 cm, 1.3-7.2). The mean NPRS improved for the shockwave therapy group (5.1 at baseline to 1.8 at 3 months) but worsened slightly for the traditional conservative treatment group (5.3 at baseline to 5.5 at 3 months; 95% CI for the difference of 3.7, 1.4-4.8). After 12 months, 80% of the patients in the shockwave therapy group were rated much improved or completely recovered and 80% had returned to their preinjury level of sport participation (mean time to return, 9 weeks; range, 6-15 weeks) compared with none in the traditional conservative treatment group. Surgical intervention was more common in the traditional conservative treatment group than the shockwave therapy group (5 patients vs 1 patient).
Shockwave therapy for athletes with hamstring tendinopathy was more effective in reducing pain and accelerating return to sport than “traditional” conservative treatment. Improvements were evident 3 and 12 months after treatment.