Original article written by Aleksi Jokela, Antti Stenroos, Jussi Kosola and colleagues
Background
Hamstring injuries continue to cause a major burden to professional athletes in elite sport. Sprinting is the most common mechanism in sport for sustaining an isolated proximal biceps femoris injury, whereas stretching-type injuries are associated with insult to the semimembranosus [1]. The degree of hamstring injury sustained can vary, ranging from a minor muscle strain to a complete avulsion of the tendinous portion of the muscle. The main cause of severe hamstring tendon avulsion is a rapid, forceful hip flexion moment with the ipsilateral knee extended.
Ten years ago, it would have been inconceivable to consider surgical intervention for a hamstring muscle injury, regardless of its severity. However, with increasing competitive pressures, advances in imaging and more sophisticated muscle grading classification systems, there has become a growing trend to consider surgery as a treatment option for higher grade hamstring injuries [2].
There has been no previous systematic review published on outcomes following surgical treatment of hamstring tendon injuries. Additionally, little is known about the outcomes of surgical treatment. The aim of this study was to analyse clinical and patient-reported outcomes following surgical repair of high-grade hamstring tendon injuries.
What the authors did
- Systematic review format – a total of 24 studies were yielded from the authors search strategy.
- The authors sought to compare the outcomes of endoscopic vs. open treatment, acute vs. chronic repairs and partial vs. complete repairs.
- The study population comprised 1602 patients with hamstring injuries. The age of the patients in the review ranged from 26 to 51 years
- 12.2% of participants were professional athletes, 27.3% competitive athletes and 49.6% were recreational athletes.
- Return to sports was used as an outcome measure in 62.5% of the included studies, patient satisfaction in 50%, and strength in 37.5%.
What the authors found
Open vs endoscopic repair
The majority of participants were treated with open surgery (96%) and a small cohort (4%) with endoscopic approach. Most patients were treated with primary repair. However, a total of 24 chronic complete avulsions were treated with repair augmented with graft.
Acute vs chronic repair
Acute avulsions were defined as patients who were treated operatively within 6 weeks of injury occurrence, while chronic avulsions underwent surgery after 6 weeks. The mean time from injury to intervention for the acute and chronic groups was 2.8 and 46 weeks, respectively.
After repair, 95% of the acutely repaired hamstrings were satisfied with their outcome, which was significantly greater compared to the chronic group (77%). Similar findings were noted in returning to sport at the same level (92% vs. 85%). Analysis of variance suggested the effect of time to surgery on return to sport was significant.
The average incidence of complications was 15.69%, with re-rupture and neurologic complications being the most common type of complications. Complication rate was higher in chronic repairs, which is consistent with previous studies. Chronic repairs had a complication rate of 25%, whereas 14% of acute repairs reported complications.
Partial vs complete avulsion repair
After repair, 92% of patients with complete ruptures were satisfied with their outcome compared to 87% with partial rupture and subsequent repair. Complete avulsions had lower pain scores.
81% of those with surgically repaired complete avulsions returned to their sport at the same level pre-injury, compared to 78% of those with partial avulsions.
Limitations
- Study findings are not exclusive to elite athletes; therefore, caution should be taken when applying the findings of this study to patients within the elite and professional sport.
- Demographics of the review included participants aged between 26-51. With such a large age range, we can expect variation in the speed and healing capacity of participants post-surgery. Thus, recovery rates will likely vary substantially. This should be considered when applying the findings of the study to our athletes.
- Patient-reported outcome measures and clinical outcome measures are important tools for evaluation of the results of surgical treatment. There is currently no gold-standard assessment tool for measuring outcomes following hamstring surgery. The heterogeneity of outcome measures within this review leads to difficulties in comparing different studies and, therefore, caution should be taken when generalising findings.
What this means for coaches
This is the largest systematic review, researching the current evidence of patient outcomes following surgical treatment of hamstring tendon injury,
Some of the most clinically relevant findings were:
- Majority of patients referred for surgery following hamstring tendon injury are currently treated with an open procedure.
- Acute repair of hamstring tendon injury leads to higher patient satisfaction than delayed repair. Acute repair also leads to better functional outcomes and lower complication rates, when compared to chronic injuries. These outcomes are likely to be reflective of acute repairs being less technically demanding for surgeons as they involve a reduced amount of scar tissue, and anatomical structures can be more easily distinguished. Greater scar tissue can also cause chronic symptoms due to the proximity of the sciatic nerve and pressure around this, which can cause both local and referred neurological symptoms.
- The amount of tendon retraction is an important factor when deciding the treatment method. The authors recommend, based on their experience and previous literature [3], that severe tendon avulsions with clear retractions are treated operatively. The threshold value for surgical treatment is often recommended to be minimum of 2cm of tendon retraction.
Reviewer’s comments
My current approach to high grade hamstring injuries is to use a shared decision-making model of care to decide if operative treatment is appropriate. Such a decision should be discussed with all stakeholders, including an experienced surgeon, weighing up the positive and negatives of both operative and non-operative management – both of which have shown successful outcomes. I have referenced some further reading below which touches on the conservative management of higher-grade hamstring injuries with tendon involvement.
Recommended resouces
Article – Proximal hamstring tendon avulsions: comparable clinical outcomes of operative and non-operative treatment at 1-year follow-up using a shared decision-making model – Anne van der Made and colleagues
Article – Hamstring rehabilitation in elite track and field athletes: applying the British Athletics Muscle Injury Classification in clinical practice – Ben Macdonald and colleagues