1 Introduction

Proximal hamstring tendon injuries, including partial and complete avulsions, are significant musculoskeletal conditions, particularly in athletes and physically active individuals.^1–3 These occur when one or more hamstring tendons detach from their origin at the level of the ischial tuberosity, often during eccentric overload caused by sudden hip flexion with the knee extended.^1,2,4–10 The biarticular nature of the hamstrings and their high proportion of type II fast-twitch muscle fibers increase their vulnerability.^4,5

While muscle strains at the myotendinous junction are typically managed conservatively, proximal tendon avulsions—especially chronic cases presenting after four weeks—may involve degenerative changes and require surgical consideration.^6–8 These injuries account for approximately 12 % of all hamstring-related injuries, with complete avulsions comprising up to 9 %.⁹

Patients typically present with acute posterior thigh pain, weakness, ecchymosis, and difficulty sitting or performing physical activity. Magnetic resonance imaging (MRI) is the gold standard for diagnosis, enabling the assessment of tendon involvement, retraction, and chronicity; however, no validated imaging-based classification system currently exists.¹¹

Non-operative management is indicated for low-grade injuries, chronic tendinopathy, or complete avulsions with minimal tendon retraction (<2 cm).¹² It includes rest, non-steroidal anti-inflammatory drugs (NSAIDs), protected weight-bearing, and physiotherapy. Recently, biologic and adjunctive therapies such as corticosteroid injections, platelet-rich plasma (PRP), dry needling, and extracorporeal shockwave therapy have been proposed for selected cases.^13–17

Surgical repair is generally indicated for complete avulsions, involvement of two or more tendons with more than 2 cm of retraction, persistent symptoms beyond six months, or in high-demand patients.^2,12,18,19 Delayed repair (>4 weeks) may be complicated by fibrosis and adherence of the sciatic nerve, reducing surgical feasibility.²⁰

Open surgical repair remains the traditional standard but is associated with complication rates up to 23 %, including neurological injury and suboptimal return to sport.¹³ Endoscopic techniques have recently emerged as a less invasive alternative in selected acute cases, potentially reducing soft tissue trauma and recovery time.^21,22 However, comparative outcomes between open and endoscopic approaches remain poorly defined.

This systematic review aims to compare the clinical and radiological outcomes of open versus endoscopic surgical repair for proximal hamstring tendon avulsions. Specifically, it evaluates differences in functional recovery, complication rates, return to sport, tendon healing, and retraction correction as assessed by imaging. Unlike previous reviews on this topic,^11,13,19 this work provides an expanded critical appraisal of comparative outcomes and offers a more balanced synthesis to clarify the relative strengths and limitations of each approach, supporting surgical decision-making.

2 Materials and methods

2.3

2.3 Search strategy and study screening

A systematic search of PubMed, Embase, Scopus, Cochrane Library, and MEDLINE was conducted using relevant MeSH terms ((hamstring*) OR (semitendinous) OR (semimembranous)) AND ((strain) OR (rupture)) AND ((arthroscop*) OR (endoscop*)). The search yielded 1801 articles; after removing 689 duplicates, 1112 records were screened. Following title and abstract review, 14 full-text articles were assessed, and five met the inclusion criteria. These studies reported on surgical methods, postoperative protocols, clinical and imaging outcomes, complications, and reoperations, comparing endoscopic and open approaches. The selection procedure is outlined in the PRISMA diagram (Fig. 1). To reduce the risk of confirmation bias, screening, data extraction, and risk-of-bias assessment were independently performed by two authors, with disagreements resolved by a third senior author.

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Fig. 1 2020 PRISMA Flow diagram of study selection. PRISMA = Preferred Reporting Items for Systematic Reviews and Meta-Analyses; NA = Not Available.

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2.4

2.4 Quality assessment

The methodological quality of the included studies was assessed using the Oxford Centre for Evidence-Based Medicine 2011 Levels of Evidence (LoE).²⁴ For retrospective designs, the risk of bias was assessed using the ROBINS-I tool^25,26 (Fig. 2). The highest judgment across all domains determined the overall risk of bias. Postoperative complications were categorized according to the Clavien–Dindo classification system.^27,28 Two independent reviewers (RGV and AE) conducted the assessments, with any disagreements resolved by a third reviewer (FB). The review protocol was pre-registered in PROSPERO (ID: CRD42024598022).²⁹

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Fig. 2 ROBINS-I risk-of-bias evaluation of included studies.

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3 Results

A total of five retrospective studies^30–34 satisfied the inclusion criteria for this systematic review. Of these, three studies^30–32 included cohorts undergoing both open and endoscopic surgical repair of proximal hamstring tendon injuries, while two studies^33,34 focused exclusively on endoscopic procedures. Overall, 181 patients undergoing unilateral hamstring repair were analyzed, with 84 treated using the open technique and 97 with the endoscopic approach. The follow-up period ranged from one to nearly eight years, capturing short-to medium-term outcomes. Detailed demographics and study characteristics are summarized in Table 1.

4 Discussion

The major finding of the present systematic review is that endoscopic repair of proximal hamstring tendon injuries is associated with a lower rate of complications and reoperations compared to the open surgical approach in the short-to medium-term follow-up period. Patient-reported outcome measures (PROMs) were consistently comparable or superior following endoscopic repair, and three out of the five included studies demonstrated favorable recovery trajectories and high satisfaction rates. In addition to prior publications on proximal hamstring repair,^11,13,19 this review adds value by specifically evaluating purely endoscopic cohorts alongside direct comparisons with open repair. By focusing on this dual perspective, it provides a more clinically oriented and updated synthesis to guide surgeons in the decision-making process.

Proximal hamstring injuries pose a unique challenge due to their anatomical complexity and functional demands, particularly at the ischial tuberosity origin 1–3. While open repair is the gold standard, it is associated with extensive soft tissue disruption, a higher incidence of wound-related complications, and prolonged rehabilitation, as is the case with all open surgeries.^12,20 In contrast, endoscopic techniques, when performed by experienced hands, offer improved visualization, targeted debridement, and tendon reattachment with minimal collateral damage.²¹ Notably, Kurowicki et al.³³ employed an endoscopic protocol that allowed for early weight-bearing as tolerated, resulting in reduced postoperative pain and improved functional outcomes. This supports the rationale for this technique in selected patients.

Nevertheless, despite growing interest and favorable short-term outcomes, a consensus remains lacking regarding the optimal surgical approach for these injuries. The open technique certainly offers advantages in terms of ease of surgical execution, but it presents problems related to open surgery itself. Endoscopic surgery overcomes this problem, but it is undoubtedly more challenging from a surgical perspective, with a significant learning curve, and should be reserved for surgeons who are experts in arthroscopy and hip endoscopy, and who perform many similar procedures. Therefore, while endoscopic repair appears promising, the open approach remains the standard of reference, particularly in complex cases or when performed by less experienced surgeons. Endoscopic repair should be considered an alternative in selected patients and reserved for surgeons with advanced arthroscopic expertise.

All studies included in this review consistently demonstrated that both open and endoscopic repair result in significant improvements in functional recovery, as measured by validated PROMs such as the mHHS, iHOT-12, HOS-ADL, and HOS-SS.^30–34 These gains were observed across different cohorts and follow-up periods, confirming that surgical repair—regardless of technique—can restore tendon function and improve patient-reported outcomes in most cases.^8,11,12 When outcomes were compared between groups, endoscopic repair generally provided results that were at least comparable to those of open surgery, with some evidence suggesting superior performance in terms of pain relief, functional recovery, and achieving clinically meaningful thresholds.^30,31,33,34 This is particularly relevant for active patients, where restoration of high-demand function and patient satisfaction are critical.^2,18

Return to pre-injury activity levels and overall satisfaction further support these findings. Although the rates of return to sport or activity varied between studies, most series reported favorable results, with satisfaction rates consistently high and exceeding 90 % in several endoscopic cohorts.^32–34 These outcomes suggest that endoscopic repair, when performed in carefully selected patients, may facilitate a more predictable recovery trajectory and higher patient acceptance compared to traditional open approaches.^21,22

Another important finding concerns the safety profile of the two procedures. Complication and revision rates were systematically lower following endoscopic repair.^30–34 This likely reflects the reduced surgical exposure, less soft tissue trauma, and better visualization of critical neurovascular structures associated with minimally invasive techniques.^20,21 These advantages align with the broader trend in orthopedic surgery toward arthroscopic and endoscopic procedures, which aim to minimize morbidity while preserving or even enhancing efficacy.^8,19,21 Nevertheless, it must be acknowledged that the open approach still represents the gold standard, particularly in complex cases such as chronic avulsions with extensive tendon retraction, or when performed by surgeons with limited experience in hip arthroscopy.^12,18,20 In these situations, open repair remains more reproducible and technically less demanding. Conversely, endoscopic repair should be reserved for specialized centers and surgeons with advanced arthroscopic expertise, where the technical challenges and learning curve can be adequately managed.^21,22

Secondary outcome measures further support the use of endoscopy. Kurowicki et al.³³ reported a marked reduction in VAS pain scores (from 5.3 ± 2.4 to 1.85 ± 2) and an increase in UCLA scores postoperatively. Wong et al.³² showed improvements in the Lower Extremity Functional Scale (LEFS), SANE, and Short Form-12 (SF-12). Fletcher et al.³⁴ reported parallel gains in the modified Harris Hip Score (mHHS) and HOS-ADL, further reinforcing the clinical effectiveness of the endoscopic approach.

This review highlights the limitations that need to be addressed. First, the included studies were few and retrospective, which introduces selection and information bias and limits the ability to draw definitive causal inferences. Notably, all included studies were Level IV retrospective designs, which markedly limits the overall strength of evidence and precludes any meta-analytic inference beyond descriptive synthesis. Second, there was notable heterogeneity in patient demographics, injury severity, surgical techniques employed, rehabilitation protocols, follow-up times, and patient selection, which impedes direct comparisons. No statistical adjustments for these variables were performed, as this would have further reduced validity given the already small number of patients included in each study. Third, follow-up durations ranged from 1 to 8 years, which limited the assessment of long-term durability. More consistent and standardized clinical follow-up could improve the validity of the data. Four, only English-language studies were included, which may have excluded relevant research and affected the generalizability of the findings. Moreover, the search strategy was limited to electronic databases, excluding gray literature, trial registries, and manual reference list reviews, which may have introduced selection bias and reduced comprehensiveness. Five, a ROBINS-I evaluation demonstrated a serious overall risk of bias across most studies, primarily due to confounding by indication and limited reporting on missing data and selective reporting.

Furthermore, the inclusion of studies reporting exclusively on endoscopic repair, although outside the strict PICOS comparative framework, was considered necessary to provide a broader overview of outcomes and to increase the available evidence base. However, this further limited direct comparability between open and endoscopic cohorts. Different patient-reported outcome measures (PROMs) were presented across studies. These instruments were not directly compared or normalized; instead, they were reported descriptively to illustrate functional outcomes, which may reduce the strength of cross-study comparisons. In addition, some endoscopic cohorts were relatively small (as low as 20 cases), reflecting the rarity of this condition and limiting the robustness of comparisons. Significant prognostic factors, such as chronicity, the number of tendons avulsed, and surgeon expertise, could not be adjusted for and may have influenced the results. Some complications, including subjective symptoms such as hamstring weakness or persistent sitting pain, were reported without objective grading but were nevertheless included in descriptive summaries. Finally, return-to-activity was variably defined across studies, often without the use of standardized scales, such as the Tegner score; therefore, these percentages should be interpreted with caution. Finally, the overall certainty of evidence was not formally graded with the GRADE approach, which represents a further limitation. These sources of heterogeneity and potential bias weaken the strength and reliability of the conclusions, so the results should be interpreted with caution and confirmed by more rigorous future randomized research.

5 Conclusion

Current evidence suggests that endoscopic repair of proximal hamstring tendon injuries may result in lower complication and reoperation rates compared to open techniques, while offering similar short-to mid-term functional outcomes and high patient satisfaction. Nonetheless, these findings must be interpreted with caution, given that all available studies are small retrospective series (Level IV), without randomized allocation and with possible selection bias in favor of endoscopic repair. The limited follow-up and heterogeneity in surgical techniques, rehabilitation protocols, and outcome definitions further weaken the evidence's strength. Future prospective multicenter randomized studies are needed to confirm these preliminary observations and to establish clear treatment recommendations.

Guardian/patient's consent

Not Applicable.

Ethical statement

The study was conducted following the ethical standards of the Declaration of Helsinki (1964).

Author statement

RGV: Conceptualization, Original draft preparation, Visualization, Project administration.

AE: Original draft preparation, Data curation.

FB: Visualization, Supervision.

CB: Data curation, Methodology, Data analysis, Formal analysis.

SV: Data curation, Methodology, Data analysis, Formal analysis.

MG: Visualization, Figure preparation, Data validation.

KZ: Visualization, Supervision, Critical revision.

KL: Visualization, Supervision.

JW: Visualization, Supervision.

AM: Visualization, Supervision.

Funding statement

No funding or grants were received for this study.