The purpose of this study is to provide reliable evidence on how to best treat proximal hamstrings avulsions, and our primary aim is to compare the reported outcome of patients treated non-operatively with patients treated with suture anchor reattachment of the tendons using the Perth Hamstrings Assessment Tool (PHAT) at 24 months.

The treatment of proximal hamstrings avulsions is controversial and patients with this injury will get treatment recommendations based not on scientific evidence but on personal preferences of their surgeon. The literature is totally devoid of studies comparing the two treatment options; non-operative and operative treatment. In Sweden, it is probably more common to treat these injuries nonoperatively. This is in contrast to existing literature that suggests that better outcomes are expected with operative treatment. However, there is a very clear publication bias in the literature. In fact, of the more than 40 published clinical studies, only a handful mentions the results of non-operatively treated injuries.

In a systematic review examining 13 original studies, patient satisfaction ranged from 88% to 100% after surgical treatment. In nine of the studies strength of hamstrings were reported and ranged from 78% to 101% of the uninjured side. However, residual pain is common, ranging from 8 to 61% in a group of 203 patients and in a recent unpublished study the lower extremity functional score were similar in patients treated by either modality. Additionally, serious nerve injuries after surgery have been reported and infection, anchor failure and re-rupture occur. The reoperation rate in a study by Sarimo et al. was 12%.

This study is a prospective, multicentre, preference-tolerant, randomized controlled, non-inferiority trial comparing operative to non-operative treatment of proximal hamstrings avulsions. The study will include a concurrent prospective observational cohort.

The eligible study population will consist of patients with an acute, avulsion of hamstrings tendons diagnosed in a hospital in Sweden, or Norway and subsequently referred to one of the study sites. All patients fulfilling the inclusion and not meeting the exclusion criteria will be asked to participate in the study. After the patient´s enrolment has been confirmed and informed consent is obtained a set of questionnaires is provided for background data on medical history, activity levels and a recall assessment of the pre-injury functional status. When these questionnaires are completed, the patient is randomized.

If the patient is randomized to non-operative treatment an appointment with a physiotherapist follows and the study rehabilitation protocol is explained. If the patient is randomized to surgery, the procedure is scheduled at the earliest convenient time but no later than 2 weeks from inclusion. The surgical procedure and rehabilitation protocol is standardized among sites. The same rehabilitation protocol is used for both treatment groups.

Participation in this study will last 24 months. In-person participant follow-up visits will occur at enrollment (baseline), at-surgery, 3 months, 6 months, 12 months and 24 months post-surgery. Data for outcomes will be collected at follow-up visit and a MRI will be performed at 24 months.

Inclusion criteria

• age of the patient at injury between 30 and 70
• MRI shows a complete avulsion of at least two of three tendons from the insertion at the ischial tubercule
• physical examination supports the diagnosis; e.g. a positive hip extension test, palpable defect and/or local tenderness and hematoma
• patient has a moderate to high activity level
• patient has linguistic and mental ability to understands study program explained in Swedish, Finnish, Norwegian or English
• time from injury to inclusion in study is less than 4 weeks

A patient with moderate to high activity level is defined as any patient that is ambulatory in the community and participates in some type of strenuous activity at work or in spare time on a regular basis. Any patient that skis, goes for an occasional run, takes long walks in the woods, climbs ladders or physically manages a large garden have an activity level that is at least moderate.

Exclusion criteria

• diabetes with secondary complications
• previous major lower extremity injury or disease with sequelae
• moderate or severe liver, pulmonary, kidney, psychiatric or heart disease that significantly increases the risk for complications after operative treatment
• severe obesity (BMI>35)
• alcohol or drug abuse
• high energy injury or combinations of injuries affecting the lower extremity

De-identified individual participant data for all primary and secondary outcome measures will be made available

Within 6 months of study completion

Data access request will be reviewed by independent University leaders. Requestors will be required to sign DAA

Personell assessing functional performance of patients are blinded.