Hamstring injuries account for 4% to 25% of sports-related muscle injuries, and partial hamstring tears are especially common during running. Over time, even low-grade proximal tears can cause debilitating pain in the back of the upper thigh and buttocks as well as loss of function, which may force people to stop running.
For many injured runners, conservative approaches like nonsteroidal anti-inflammatories (NSAIDs), steroid injections and physical therapy fail to control the pain associated with proximal hamstring tears. Although surgery is the gold standard for acute traumatic injuries involving a complete hamstring tear, surgeons may hesitate to recommend surgical repair of lower-grade proximal tears that develop over time. These runners and athletes are often forced to deal with ongoing pain and an inability to participate in their sport of choice.
“Until recently, there hasn’t been enough outcomes data for us to provide a good answer for patients with these chronic, exertional, attritional injuries,” says Shane J. Nho, MD, MS, an orthopedic surgeon focused on sports medicine and arthroscopic treatment of the hip, shoulder and knee at Rush University Medical Center.
Challenging the gold standard
Endoscopic hamstring repair has emerged as a minimally invasive alternative to the open approach since it was first described by Dierckman et al. in 2012. Since then, a growing body of evidence has demonstrated that endoscopic repair can effectively restore function and reduce pain, with high return-to-sport rates ranging from 77% to 95%. Only one 2019 study by Bowman et al. focused on runners with proximal hamstring tears who had either an open or endoscopic approach, finding that 82% were able to return to running.
Potential advantages of endoscopic repair over the open approach include smaller incisions and better visualization of the sciatic nerve, Nho says. Fenn et al. found endoscopic repair had fewer complications such as infections (0% for endoscopic versus 6% for open) and neuropathy (3% versus almost 9%).
Fenn et al. also found that for lower-grade tears in particular, endoscopic repair may result in higher patient acceptable symptom state (PASS) achievement for patient-reported outcomes (PROs) — including the Hip Outcome Score-Activities of Daily Living/Sports Subscale (HOS-ADL/SS) and international Hip Outcome Tool-12 item questionnaire (iHOT-12) — compared with the open approach. Yet the effects on patients’ ability to return to running (RTR) following endoscopic surgery have not been widely investigated.
The aims of the study
Nho and his colleagues embarked on this first-of-its-kind case series to report complications, reoperations and PROs specifically in runners following endoscopic hamstring repair. PROs collected included the HOS-ADL/SS, iHOT-12 and the Visual Analog Scale for Pain (VAS-Pain). Researchers evaluated PROs against previously published thresholds to determine PASS achievement.
Using a patient survey given one year or more following surgery, Nho’s team also aimed to determine the RTR rate and changes in miles run per week between runners at baseline, post-injury/pre-surgery and after endoscopic repair.
Patient selection
The study included 20 patients who had endoscopic hamstring repair from 2017 to 2022. The average age of patients was 40, and nearly two-thirds were female.
Most (16) patients had incomplete hamstring tears with at least one tendon that remained attached. Tears were considered chronic if they lasted more than four weeks prior to surgery.
The results
Of the 20 runners with chronic proximal hamstring tears, 16 (80%) returned to running at an average of six months after endoscopic repair. Among the four (20%) who were not able to return to running, three had hamstring pain that persisted after surgery, and another had pain in other joints.
At baseline, patients’ mean running distance was 14.5 miles/week, which dropped to 5.4 miles per week after injury. After surgery, mean running distance actually increased to 17.9 miles per week. “While the aim of many surgical interventions is to get patients back to where they were before the injury, most patients who had endoscopic hamstring repair actually exceeded their baseline running distance,” Nho says. This finding contrasts with results from the Bowman study, which found that runners having open or endoscopic repair were not able to run the same distance as before their injury.
Only one patient in Nho’s study required a reoperation because of a traumatic retear. No other complications occurred, which is consistent with other studies demonstrating a low rate of postoperative complications.
One finding from the research that surprised Nho and his team was the 100% PASS achievement rate for at least one PRO, indicating a significant improvement in PROs and a high rate of patient satisfaction for their levels of pain, strength and function following the surgery. “In this particular series, 100% of patients said their function was acceptable postoperatively,” Nho says.
The next steps
Although most of the runners in this series had lower-grade tears, Nho believes future research on endoscopic repair that includes more patients with higher-grade tears could provide a better understanding of the potential benefits and limitations of endoscopic repair for a wider population.
Future research might also involve more granular preoperative testing of patients’ strength and function as well as conducting additional imaging studies, such as ultrasound, before surgery. “With that knowledge, we could better counsel our patients and help them weigh the positives and the negatives of surgery based on their own particular anatomy or situation,” says Nho, who also co-directs the Division of Sports Medicine and the Sports Medicine Fellowship at Rush.
Despite the recent advances in minimally invasive surgical repair of proximal hamstring injuries, many runners with hamstring tears do not know their condition is treatable. “Patients may be suffering or feel like their level of activity has been compromised by their injury,” Nho says. “But there is a surgical option with newer, innovative techniques that are less invasive and are associated with smaller incisions, less pain and a faster recovery.”
