Abstract
Background
Meniscal repair has increasingly replaced meniscectomy because of its superior long-term clinical outcomes and protective effects against osteoarthritis. The inside-out technique is widely considered the gold standard due to its strong biomechanical fixation and versatility. However, the conventional technique requires a posteromedial or posterolateral safety incision to protect neurovascular structures, which increases surgical invasiveness and technical complexity. This study aimed to evaluate the clinical and MRI outcomes of a percutaneous modification of the inside-out technique that eliminates the need for a formal posterior safety incision.
Methods
This retrospective cohort study included 61 patients who underwent isolated meniscal repair using the percutaneous inside-out technique between January 2022 and January 2023 with a minimum follow-up of 24 months. Clinical and radiological outcomes were evaluated using magnetic resonance imaging (MRI), International Knee Documentation Committee (IKDC) and Lysholm scores, McMurray testing, and neurological examination.
Results
Postoperative MRI demonstrated complete healing in 62.3% and partial healing in 9.8% of patients, yielding an overall healing rate of 72.1%. Functional success was achieved in 90.2% of patients according to IKDC scores and 88.5% according to Lysholm scores, with a combined success rate of 77.0%. Neurological complications occurred in 9.8% of patients and were not associated with the stab incision site. Higher Lysholm scores, non-smoking status, left-sided surgery, longitudinal or horizontal tear patterns, and a negative postoperative McMurray test were identified as independent predictors of MRI healing. Conversely, higher IKDC scores showed an inverse association with MRI healing grades. ROC analysis demonstrated that the Lysholm score had good discriminative ability for detecting neurological deficits (AUC = 0.767; cut-off = 91; sensitivity = 83.3%, specificity = 69.1%).
Conclusion
The percutaneous inside-out technique demonstrated favorable clinical and MRI outcomes while avoiding the need for a formal posterior safety incision. This approach may represent a reliable and minimally invasive alternative to conventional inside-out meniscal repair techniques.
Keywords: Meniscus repair, Inside-out technique, Percutaneous surgery, Arthroscopy, Knee joint
Background
The meniscus plays a crucial role in maintaining normal knee biomechanics by contributing to load transmission, joint stability, lubrication, and protection of the articular cartilage [1]. Meniscal tears are among the most common knee injuries and often require surgical treatment due to persistent pain and mechanical symptoms [2, 3], accounting for approximately 10–20% of orthopedic procedures performed annually in the United States [4]. Current treatment strategies have shifted from meniscectomy toward meniscal preservation, as meniscal repair has been shown to provide better long-term outcomes, allow higher functional activity levels, and delay the development of osteoarthritis compared with partial meniscectomy [5].
Three primary techniques are used for meniscal repair: outside-in, all-inside, and inside-out, with the latter two being the most commonly performed [6]. First described by Henning [7], the inside-out technique is widely considered the gold standard for meniscal repair due to its superior biomechanical strength, versatility, and cost-effectiveness [8, 9]. It allows the placement of multiple sutures using fine-gauge needles, creating a strong repair construct without compromising meniscal integrity [2, 8]. Therefore, it is often recommended for a wide range of repairable meniscal tears, particularly those involving the meniscal body and posterior horn [9, 10].
Despite its proven efficacy, the conventional inside-out technique has notable drawbacks. It requires an additional “safety incision” at the posteromedial or posterolateral aspect of the knee to protect vital neurovascular structures—such as the saphenous nerve and vein medially and the common peroneal nerve laterally—as the suture needles exit the joint capsule [9]. However, this requirement increases the procedure’s invasiveness, prolongs operative time, elevates technical complexity, and typically necessitates assistance from an experienced surgical aide for needle retrieval and tissue retraction [11].
Recent efforts have sought to reduce the invasiveness of the traditional inside-out approach. Laupattarakasem et al. introduced a hybrid inside-out/outside-in technique using a smaller incision [12], while Kambhampati et al. described a simple, low-cost method employing a hollow needle through a single stab incision [13]. These refinements reflect a clear trend toward minimizing surgical morbidity while preserving the biomechanical benefits of the gold-standard method.
The present study reports the clinical outcomes of a modified inside-out meniscal repair that replaces the large safety incision with a percutaneous stab incision. We hypothesized that this approach would achieve clinical and radiological results comparable to those of the standard inside-out repair while reducing morbidity associated with the safety incision.
Methods
This retrospective cohort study included consecutive patients who underwent isolated meniscal repair using the percutaneous inside-out technique between January 2022 and January 2023 and had a minimum postoperative follow-up of 24 months. Ethical approval was obtained from the Non-Interventional Research Ethics Committee of İzmir Tepecik Training and Research Hospital (Approval No: 2025/04–12; Date: May 2, 2025). Due to the retrospective nature of the study, the requirement for informed consent was waived by the ethics committee. The study was conducted in accordance with the principles of the Declaration of Helsinki.
This retrospective cohort included adult patients (≥ 18 years) who underwent inside-out meniscal repair. Only patients with a minimum of two years of postoperative follow-up were included. Eligible cases involved repairable meniscal tears located in the red-red, red-white vascular zones, as confirmed intraoperatively, and tear patterns such as bucket-handle, vertical, horizontal, radial types. Patients with prior surgery on either knee, those who underwent other meniscal repair techniques such as partial meniscectomy, root repair, or procedures for irreparable tears, and those with associated fractures, ligament reconstructions (ACL or PCL), multiple-ligament injuries, cartilage restoration, or clinically unstable knees and those without postoperative MRI performed at 24 months of follow-up were excluded. Full-length standing radiographs evaluating lower limb mechanical alignment were not routinely available for all patients; therefore, lower limb alignment was not included in the analysis.
At the 2-year follow-up, all patients underwent comprehensive clinical and radiological assessment. Postoperative magnetic resonance imaging (MRI) was performed for all patients using a 1.5-Tesla MRI system. All MRI scans were evaluated by an experienced radiologist who was blinded to the patients’ clinical outcomes. Physical examination included joint line tenderness and the McMurray test to evaluate meniscal pathology. Functional outcomes were assessed using the International Knee Documentation Committee (IKDC) and Lysholm scoring systems [14, 15].
Superficial sensation was assessed using light-touch and pinprick discrimination tests at three regions around the stab incision sites (anterior, middle, and posterior). For light-touch testing, a small piece of cotton or gauze was gently brushed across the skin surface, and the patient was asked to report perception of the stimulus. Pinprick testing was performed using alternating blunt and sharp objects to assess discrimination ability. Sensory findings were compared with the contralateral limb and recorded as present or absent in each region. A sensory deficit was defined as decreased or absent perception of light touch or impaired sharp–dull discrimination compared with the contralateral side. All examinations were performed by a single orthopedic surgeon to ensure consistency and minimize interobserver variability. Patients without complete 2-year MRI data were excluded from the final analysis. Postoperative MRI healing was evaluated according to the study of Zicaro et al. In this study, complete healing was defined as normal meniscal morphology without a visible gap and homogeneous low-signal intensity, partial healing as a residual gap < 2 mm accompanied by minimal intrameniscal hyperintensity, and non-healing as a persistent gap ≥ 2 mm or a linear hyperintense signal extending to the meniscal surface on T2-weighted images [16] (Fig. 1a–d).
Fig. 1.
Postoperative MRI evaluation of meniscal healing. a Coronal T2-weighted MRI of the medial meniscus showing complete healing with normal meniscal morphology and homogeneous low-signal intensity. b Sagittal T2-weighted MRI of the medial meniscus showing complete healing with restored contour and uniform low-signal intensity. c Coronal T2-weighted MRI demonstrating non-healing with residual intrameniscal hyperintensity at the repair site. d Sagittal T2-weighted MRI demonstrating non-healing with a persistent linear hyperintense signal extending to the meniscal surface
Surgical technique
All procedures were performed by an orthopedic surgeon with 15 years of experience in sports surgery. The procedures were carried out under regional anesthesia with the patient in the supine position. Standard diagnostic arthroscopy was first performed, followed by tear preparation using a rasp or shaver to stimulate healing.
Meniscal repair was performed using a percutaneous modification of the conventional inside-out technique. Vertical mattress sutures were primarily used for longitudinal tears to provide fixation perpendicular to the tear line, whereas horizontal mattress sutures were preferred for horizontal cleavage tears to achieve stable compression between the superior and inferior meniscal leaflets (Fig. 2).
Fig. 2.
Arthroscopic view of a repaired medial meniscus following percutaneous inside-out meniscal repair, demonstrating stable reduction of the tear
All repairs were performed using a double-needle inside-out meniscal repair system (Tulpar®, Türkiye). The system consists of two long stainless-steel needles connected by a USP 2 − 0 ultra–high–molecular-weight polyethylene–reinforced suture and includes both straight and curved guiding systems to facilitate controlled passage through the meniscal tissue and capsule.
Sutures were passed using cannulae without creating additional posteromedial or posterolateral safety incisions. The needles were advanced across the tear and retrieved percutaneously through the skin. When the exiting needles were located close to each other, they were retrieved through the same stab incision using an arthroscopic probe, allowing multiple sutures to be managed through a limited number of small incisions. This approach eliminated the need for a formal posteromedial or posterolateral safety incision and avoided extensive soft-tissue dissection.
After both needles were retrieved, the two ends of the same suture were secured temporarily with a clamp to prevent suture entanglement. Stab incisions were created according to the number and location of the sutures. Following blunt subcutaneous dissection toward the capsular level using a fine-tipped clamp, the suture limbs were retrieved through the stab incision with the assistance of an arthroscopic probe (Fig. 3a–d).
Fig. 3.
Intraoperative views of the percutaneous inside-out medial meniscal repair technique. a Arthroscopic view showing long double needles passed through the medial meniscus and retrieved directly through the skin without a posteromedial safety incision; the free ends of each suture are temporarily secured with clamps to prevent entanglement. b Intraoperative photograph showing creation of a small medial stab incision after all sutures have been passed percutaneously, followed by blunt subcutaneous dissection toward the capsule with a fine-tipped clamp. c Intraoperative photograph demonstrating retrieval of the percutaneously passed sutures through the stab incision using an arthroscopic probe to prepare for extra-articular knot tying. d Final appearance of the medial aspect of the knee after percutaneous inside-out repair; the small stab incisions have been closed and all knots are tied extra-articularly and buried subcutaneously
During lateral meniscal repair, special attention was paid to the relationship between the sutures and the iliotibial band. After the needles exited the capsule, blunt dissection was performed toward the capsular level, and an arthroscopic probe was advanced along the axis of the iliotibial band to pass beneath it and reach the capsule. The sutures were subsequently retrieved and tied at the capsular level to avoid knot placement over the iliotibial band or other superficial soft tissues. This approach also allowed the procedure to be performed without the need for an additional surgical assistant for needle retrieval or tissue retraction.
Extracapsular knots were tied using the RevoKnot sliding knot technique under direct arthroscopic visualization to ensure appropriate tensioning of the repair and stable fixation of the meniscal tissue.
The medial and lateral aspect of the knee was divided into three equal zones (A: anterior, M: middle, P: posterior) for standardized suture documentation. Sutures were typically placed at approximately 4–6 mm intervals along the tear to ensure adequate reduction and stable fixation of the meniscal edges. The total number of sutures used per repair was determined intraoperatively according to the tear length and stability of the repair construct.
Postoperative care
Patients undergoing isolated meniscal repair were mobilized with partial weight-bearing as tolerated from the first postoperative day. All patients were fitted with an adjustable range-of-motion knee brace, initially allowing 0°–30° of flexion during the first week. The flexion limit was gradually increased to 60° at the third week and 90° at the fourth week. By the sixth week, a full range of motion was permitted. Weight-bearing was progressively advanced to full according to the patient’s tolerance and clinical findings.
Follow-up schedule
Patients were usually discharged on the first postoperative day. Clinical evaluations were systematically performed at 15 days, 45 days, 3 months, 6 months, and 12 months. At 2 years postoperatively, all patients included in the study underwent magnetic resonance imaging (MRI), physical examination, McMurray testing, and functional assessment with the IKDC and Lysholm scoring systems. Additionally, stab incision sites were evaluated in three distinct regions (middle, anterior, and posterior), and possible neurological deficits were assessed. Patients without follow-up MRI were excluded from the study.
Statistical analysis
All statistical analyses were performed using SPSS Statistics (version 24; IBM Corp., Armonk, NY, USA). Descriptive statistics were calculated for demographic and clinical variables, including sex, smoking status, operative side, tear type, incision zone, neurological findings, MRI healing status, and McMurray test results. The distribution of continuous variables was assessed using the Kolmogorov–Smirnov and Shapiro–Wilk tests. Non-normally distributed data were compared using the Mann–Whitney U and Kruskal–Wallis tests, whereas categorical variables were analyzed with the Chi-square or Fisher’s exact test, as appropriate. Associations between incision zone, neurological examination, McMurray test results, MRI healing, and functional scores were further examined. Ordinal logistic regression was employed to identify independent predictors of higher MRI healing grades while stepwise binary logistic regression was applied to determine independent factors associated with neurological findings. Receiver operating characteristic (ROC) curve analysis was performed for the Lysholm score and a correlation between the IKDC and Lysholm scores was demonstrated using Spearman’s correlation. A post-hoc power analysis was performed based on the difference in Lysholm scores between patients with negative and positive McMurray tests. This comparison demonstrated a very large effect size (Cohen’s d = 1.70). Using α = 0.05 and the actual sample sizes of the two groups (45 vs. 16 patients), the achieved statistical power (1–β) exceeded 0.99. These findings indicate that the total sample size of 61 patients was sufficient to detect clinically meaningful differences between groups. A p-value < 0.05 was considered statistically significant.
Results
A total of 306 knee arthroscopies were performed during the study period, of which 82 involved isolated meniscal repair using the percutaneous inside-out technique. After excluding 21 patients due to incomplete follow-up or missing MRI data, 61 patients were included in the final analysis (Fig. 4).
Fig. 4.
Flow diagram showing the selection process of the final study cohort; of the 306 knee arthroscopies performed during the study period, 82 involved isolated meniscal repair with the percutaneous inside-out technique, and 61 patients with complete 2-year clinical and MRI follow-up were included in the final analysis
The mean age was 31.0 ± 6.4 years (range, 18–52), with 55.7% male and 27.9% active smokers. Most tears were located in the medial meniscus (80.3%), and the most common tear configurations were longitudinal (27.9%) and horizontal (27.5%). The mean number of sutures used per repair was 3.1 ± 1.4. At final follow-up, functional outcomes were favorable, with a mean IKDC score of 90.0 ± 10.4 and a mean Lysholm score of 91.6 ± 8.7. Detailed demographic and operative characteristics are summarized in Fig. 5.
Fig. 5.
Distribution of demographic and clinical characteristics of the study cohort, including age, sex, smoking status, meniscus side, tear configuration, and number of sutures used per repair
MRI outcomes
Postoperative MRI evaluation demonstrated satisfactory healing in the majority of patients. A significant association was found between postoperative McMurray test results and MRI healing status (χ² = 12.86, p = 0.002), indicating that patients with negative McMurray tests were more likely to achieve complete healing. These findings were supported by higher IKDC and Lysholm scores among patients with negative McMurray results (both p < 0.001) (Table 1).
Table 1.
Relationship between postoperative McMurray test results, MRI healing, and functional scores
| Variable | Negative McMurray (n = 45) | Positive McMurray (n = 16) | Test statistic | p-value |
|---|---|---|---|---|
| MRI healing status | ||||
| Complete | 34 (75.6%) | 4 (25.0%) | χ² = 12.86 | 0.002 |
| Partial | 4 (8.9%) | 2 (12.5%) | ||
| None | 7 (15.6%) | 10 (62.5%) | ||
| Functional outcomes | ||||
| IKDC score (mean ± SD) | 93.1 ± 8.2 | 79.5 ± 9.7 | Mann–Whitney U = 103.0 | < 0.001 |
| Lysholm score (mean ± SD) | 94.5 ± 6.9 | 80.2 ± 8.9 | Mann–Whitney U = 110.5 | < 0.001 |
Data are presented as number (percentage) or mean ± standard deviation. MRI healing and functional scores were assessed at the final follow-up
p < 0.05 was considered statistically significant
Functional outcomes
Functional recovery was favorable across the cohort. Mean postoperative IKDC and Lysholm scores indicated excellent function, and both scales showed a strong positive correlation (Spearman r = 0.822, p < 0.001), confirming the consistency of the two functional assessment tools (Fig. 6).
Fig. 6.
Correlation between IKDC and Lysholm scores at final follow-up, demonstrating a strong positive relationship between the two functional outcome measures (Spearman r = 0.822)
Neurological and local findings
Postoperative neurological deficits, characterized as sensory disturbances in the distribution of the saphenous nerve, were identified in six patients (9.8%). Local tenderness at the stab incision site was also reported in thirteen patients (21.3%). Among those with neurological symptoms, three patients experienced complete resolution by the 6-month follow-up, and two more by the 1-year examination, leaving only one patient with mild residual numbness at final follow-up. Patients presenting with neurological findings demonstrated significantly lower functional outcomes compared with those without deficits, as evidenced by reduced Lysholm scores (p = 0.031). Receiver operating characteristic (ROC) analysis demonstrated that the Lysholm score had good discriminative ability for identifying patients with neurological deficits, with an area under the curve (AUC) of 0.767, corresponding to a cut-off of 91 (sensitivity 83.3%, specificity 69.1%) (Fig. 7).
Fig. 7.
Receiver operating characteristic (ROC) curve for the Lysholm score in detecting postoperative neurological deficits, showing good discriminative ability with an area under the curve (AUC) of 0.767 and an optimal cut-off value of 91 (sensitivity 83.3%, specificity 69.1%)
When the relationship between stab incision region and neurological status was analyzed (Table 2), no statistically significant association was observed (p = 0.354). Neurological findings appeared slightly more frequent in the posterior and middle zones, whereas no cases occurred in the anterior zone. Similarly, the presence of local tenderness did not differ significantly among incision regions. Although tenderness rates were marginally higher in the anterior and middle zones compared with the posterior zone, these variations were not statistically significant (p = 0.728). A combined analysis of both parameters (Table 3) further confirmed that the incision region had no significant effect on either neurological findings or local tenderness. The posterior region demonstrated the lowest frequency of tenderness, while the anterior region remained free of neurological deficits.
Table 2.
Association between incision region and presence of neurological findings
| Variable | No Neurological Deficit (n = 55) | Neurological Deficit (n = 6) | Test Statistic | p-value |
|---|---|---|---|---|
| Functional outcomes | ||||
| IKDC score (mean ± SD) | 91.0 ± 9.8 | 82.7 ± 11.4 | Mann–Whitney U = 134.0 | 0.074 |
| Lysholm score (mean ± SD) | 93.1 ± 8.4 | 80.2 ± 9.6 | Mann–Whitney U = 116.5 | 0.031 |
| Local tenderness | χ² = 0.41 | 0.521 | ||
| Absent | 44 (80.0%) | 4 (66.7%) | ||
| Present | 11 (20.0%) | 2 (33.3%) | ||
| Stab incision zone | χ² = 2.07 | 0.354 | ||
| Posterior | 22 (40.0%) | 3 (50.0%) | ||
| Middle | 18 (32.7%) | 3 (50.0%) | ||
| Anterior | 15 (27.3%) | 0 (0.0%) | ||
Data are presented as number (percentage) or mean ± standard deviation. Fisher’s exact test or Chi-square test was used for categorical variables, and the Mann–Whitney U test for continuous variables
p < 0.05 was considered statistically significant
Table 3.
Combined analysis of neurological findings and local tenderness according to stab incision region
| Stab incision region | No neurological finding (n, %) | Neurological finding (n, %) | No local tenderness (n, %) | Local tenderness (n, %) | Total (n) |
p-value* (Neurological findings/ Local tenderness) |
|---|---|---|---|---|---|---|
| Posterior | 22 (88.0%) | 3 (12.0%) | 21 (84.0%) | 4 (16.0%) | 25 | 0.417 / 0.728 |
| Middle | 18 (85.7%) | 3 (14.3%) | 16 (76.2%) | 5 (23.8%) | 21 | |
| Anterior | 15 (100.0%) | 0 (0.0%) | 11 (73.3%) | 4 (26.7%) | 15 | |
| Total | 55 (90.2%) | 6 (9.8%) | 48 (78.7%) | 13 (21.3%) | 61 |
* Fisher’s exact test (two-sided): Neurological findings p = 0.417; Local tenderness p = 0.728
Patients with neurological findings exhibited significantly lower Lysholm scores compared with those without deficits (p = 0.031).
Predictors of MRI healing
Ordinal logistic regression analysis identified several independent predictors of postoperative MRI healing. Higher Lysholm scores, non-smoking status, surgery on the left side, longitudinal or horizontal tear patterns, and a negative postoperative McMurray test were independently associated with increased odds of complete MRI healing. Conversely, higher IKDC scores showed an inverse association with MRI healing grades, suggesting a possible dissociation between global knee function and radiological meniscal healing (Table 4). Other variables, including age, sex, meniscus side, suture number, incision site, and local tenderness, were not significant predictors.
Table 4.
Ordinal logistic regression analysis of factors associated with MRI healing
| Variable | β coefficient | Odds Ratio (OR) | 95% Confidence Interval (CI) | Wald | p-value |
|---|---|---|---|---|---|
| Lysholm score | 0.615 | 1.85 | 1.29–2.65 | 11.19 | 0.001 |
| IKDC score | –0.462 | 0.63 | 0.48–0.84 | 9.84 | 0.002 |
| Smoking status (non-smoker) | 1.91 | 6.77 | 1.03–44.5 | 3.97 | 0.046 |
| Operative side (left) | 2.52 | 12.4 | 1.34–115.7 | 4.91 | 0.027 |
| Longitudinal meniscal tear | 1.51 | 4.52 | 1.15–17.7 | 4.02 | 0.031 |
| Horizontal meniscal tear | 1.36 | 3.88 | 1.04–14.4 | 4.66 | 0.042 |
| McMurray test (negative) | 5.05 | 157.4 | 5.41–453.7 | 8.66 | 0.003 |
| Age | –0.031 | 0.97 | 0.89–1.06 | 0.11 | 0.421 |
| Sex (male) | 0.207 | 1.23 | 0.36–4.13 | 0.03 | 0.746 |
| Meniscus side (medial) | –0.116 | 0.89 | 0.21–3.74 | 0.17 | 0.874 |
| Number of sutures | 0.077 | 1.08 | 0.75–1.56 | 0.28 | 0.662 |
| Incision site | — | — | — | 0.25 | 0.327 |
| Local tenderness (present) | –0.342 | 0.71 | 0.18–2.74 | 2.96 | 0.086 |
Data were analyzed using ordinal logistic regression. β represents the log odds coefficient; OR = e^β. p < 0.05 was considered statistically significant. OR > 1 indicates a positive association with higher MRI healing categories
CI confidence interval, IKDC International Knee Documentation Committee
Discussion
The most important finding of this study is that the stab-incision inside-out technique for meniscal repair provided favorable MRI healing and functional outcomes without the need for a formal posterior safety incision. In our cohort, the technique achieved high healing rates and excellent functional scores, while maintaining a neurological complication profile comparable to that reported for the conventional inside-out method. Importantly, the observed neurological symptoms were infrequent and were not directly related to the stab incision site.
The conventional inside-out meniscal repair, while regarded as a gold standard for its robust repair strength, necessitates a posterior safety incision [9]. This approach increases surgical time, may raise cosmetic concerns, and often requires an experienced assistant for retraction and suture management [9]. The stab incision technique investigated in this study effectively addresses these practical disadvantages by eliminating the need for the safety incision. Our results demonstrate that this modification yields significant benefits in surgical efficiency without compromising safety or efficacy.
A potential concern when omitting a formal safety incision is the risk of neurovascular injury, particularly to the saphenous nerve medially and the peroneal nerve laterally. In our technique, this risk was mitigated by careful blunt dissection to the capsular level and controlled suture retrieval using an arthroscopic probe. The observed rate of transient sensory symptoms in our cohort was comparable to the approximately 9% rate of nerve irritation or neuropraxia reported for the conventional inside-out technique, despite the latter’s use of protective incisions [17]. These findings suggest that a carefully performed percutaneous approach may provide a comparable safety profile while avoiding the additional soft-tissue dissection required for formal safety incisions.
Anatomical MRI studies have demonstrated that ACL-injured knees show significantly reduced distance between the common peroneal nerve and the posterolateral capsule, increasing the likelihood of nerve irritation during lateral inside-out repairs [18]. Because ACL-deficient cases were excluded in the present cohort, this high-risk scenario was avoided, allowing for a more accurate evaluation of complications specifically related to the stab-incision technique. Furthermore, comparative clinical trials have reported transient saphenous nerve injuries even when a formal safety incision is used [19]. Taken together, these findings support that meticulous blunt dissection using a limited stab incision can provide a neurovascular safety profile comparable to the traditional inside-out method, while eliminating the morbidity associated with a posterior safety incision.
Another potential criticism of a limited incision technique involves the risk of inadequate suture handling, such as soft tissue interposition or failed knot advancement, which could theoretically compromise repair tension and healing. This is particularly relevant for tears near the posterior meniscal root, where the necessity for all-inside device support remains a limitation of our method. However, postoperative MRI evaluation demonstrated an overall healing rate of 72.1%, including 62.3% complete healing and 9.8% partial healing. These rates are favorable compared with the 61% healed rate reported by Zicaro et al. for inside-out repairs at a mean follow-up of 7 years [16], indicating that the stab incision technique can achieve healing outcomes comparable to those reported for conventional inside-out repair.
However, the results of the present study should also be interpreted in the context of modern all-inside meniscal repair techniques. All-inside devices have gained popularity because they eliminate the need for accessory posterior incisions and facilitate suture deployment. However, these systems are typically associated with higher implant costs and may introduce device-related complications such as implant irritation, breakage, chondral injury, or cyst formation after meniscal repair [20]. In contrast, the inside-out technique remains widely regarded as the gold standard because of its strong biomechanical fixation and cost-effectiveness. The percutaneous modification described in this study aims to combine the advantages of both approaches by preserving the biomechanical reliability of inside-out repair while minimizing the need for extensive posterior dissection.
The inverse association between IKDC scores and MRI healing observed in our study reflects the well-described mismatch between structural and functional recovery after meniscal repair. Previous studies have also reported that MRI findings may not consistently correlate with patient-reported outcomes, despite generally favorable clinical results [17]. This discrepancy may partly relate to the broader scope of the IKDC score, which reflects overall knee function rather than meniscus-specific recovery [14], whereas the Lysholm score more directly captures meniscus-related symptoms and therefore showed a positive correlation with MRI healing in our cohort [15]. Despite this variability between structural and functional parameters, the overall clinical outcomes were favorable. Our functional results are consistent with previous studies reporting excellent postoperative IKDC and Lysholm scores after isolated inside-out repairs, supporting the durability and clinical effectiveness of this technique [21–23].
From a clinical perspective, this technique may offer a less invasive alternative to conventional inside-out repair by eliminating the need for a formal posterior safety incision while preserving favorable healing and functional outcomes. From a practical surgical standpoint, the percutaneous approach may simplify the inside-out repair procedure by reducing the need for extensive posterior dissection and surgical assistance, while maintaining the biomechanical advantages of the traditional technique.
This study has several limitations that warrant consideration. First, its retrospective design and the relatively short two-year follow-up period may not fully capture long-term failure rates or the progression of osteoarthritis. Second, the absence of a concurrent control group limits the ability to directly compare this technique with conventional inside-out or all-inside meniscal repair methods. The single-center, single-surgeon design enhances internal consistency but may limit the generalizability of our findings. In addition, the assessment of healing was based on MRI, which, although objective, is not equivalent to the gold standard of second-look arthroscopy. Furthermore, lower limb mechanical alignment was not routinely evaluated using full-length standing radiographs; therefore, unrecognized varus or valgus malalignment could have influenced meniscal healing and clinical outcomes, representing a potential confounding factor. Functional outcomes were measured using patient-reported scores, which are inherently subjective. Additionally, postoperative activity level was not assessed using the Tegner Activity Scale, which could have provided further insight into return to sports and activity level after surgery. Future prospective, randomized controlled studies comparing this technique directly with conventional inside-out and all-inside repair methods, with longer follow-up durations, are necessary to validate its clinical value and long-term protective benefits for the knee joint.
Conclusion
The percutaneous inside-out technique for isolated meniscal repair demonstrated favorable clinical and MRI outcomes, supporting its reliability as a meniscus-preserving approach. The technique allowed effective meniscal repair without the need for a formal posteromedial or posterolateral safety incision, while maintaining a low complication rate comparable to conventional inside-out repairs. These findings suggest that the percutaneous inside-out method may represent a less invasive alternative that preserves the established biomechanical advantages of the traditional technique. Further prospective multicenter studies with longer follow-up are required to confirm these results and define its broader clinical applicability.
Acknowledgements
The authors thank the radiology department staff for their assistance with MRI acquisition and evaluation.
Clinical trial number
Not applicable.
Authors' contributions
EY conceived and designed the study, performed the surgical procedures, collected the data, and drafted the manuscript. MB contributed to data interpretation and critical revision of the manuscript. AÖD contributed to data collection, patient follow-up, and clinical outcome evaluation. OP performed the statistical analysis and contributed to data interpretation. VZ performed radiological evaluation and MRI healing assessment. AT contributed to surgical assistance, methodological support, and literature review. All authors read and approved the final manuscript.
Funding
No funds, grants, or other support was received.
Data availability
The datasets generated and/or analyzed during the current study are not publicly available due to the inclusion of clinical data and patient confidentiality requirements but are available from the corresponding author on reasonable request.
Declarations
Ethical approval and consent to participate
Was obtained from the Non-Interventional Research Ethics Committee of İzmir Tepecik Training and Research Hospital (Approval No: 2025/04–12; Date: May 2, 2025). Due to the retrospective nature of the study, the requirement for informed consent was waived by the ethics committee. The study was conducted in accordance with the principles of the Declaration of Helsinki.
Consent for publication
Not applicable.
Competing interests
The authors declare no competing interests.
Footnotes
Publisher’s note
Springer Nature remains neutral with regard to jurisdictional claims in published maps and institutional affiliations.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The datasets generated and/or analyzed during the current study are not publicly available due to the inclusion of clinical data and patient confidentiality requirements but are available from the corresponding author on reasonable request.