Introduction

Medial meniscus posterior root tears (MMPRT) account for 10.1–27.8% of all medial meniscus tears [1,2,3]. An avulsion of the tibial insertion of the meniscus or a radial tear close to the meniscal insertion is defined as the meniscal root tear (MRT). These injuries typically involve the posterior meniscal insertions/near the root (radial tears), with the posterior horn being most frequently affected [4]. Medial meniscus posterior root tears (MMPRT) have been reported to be functionally similar to a total meniscectomy [1, 5, 6] and integrity of the meniscus roots are critical for the ability of the meniscus to absorb hoop stress, to prevent tibiofemoral contact and meniscal extrusion [7]. Meniscal extrusion is defined as the greatest distance from the most peripheral aspect of the meniscus to the border of the tibia, excluding any osteophyte [8, 9]. The common causes of meniscal extrusion are root tears, large radial tear (> 50% of meniscal width) and large complex tears (> 1 cleavage plane through the meniscus) [10, 11]. Meniscal extrusion can independently cause knee pain apart from the primary pathology (root tear). After the meniscus has extruded, the femoral condyle and the tibial plateau comes into contact can lead to loss of tibiofemoral articular cartilage and acceleration of arthrosis [12]. Meniscus extrusion is a consistent magnetic resonance imaging (MRI) finding in knees with MMPRTs [8] and it is considered significant if there is more than 3 mm of displacement with respect to the central margin of the medial tibial plateau [13]. In addition, it has been shown that greater meniscus extrusion is a significant predictor for the progression of osteoarthritis in the knees [8]. Hence, many prefer surgical management and, currently, the most commonly used technique for root repair is arthroscopic trans-tibial pull-out repair (ATPR) [14]. Meniscus extrusion reduction/correction described by Marzo JM et al. [15] and Chernchujit [16] is a trans-osseous technique. Patients with decreased meniscus extrusion have more favourable clinical and radiographic outcomes than those with increased extrusion at 1-year follow-up [17] and, therefore, one of the main objective of the repair of MMPRTs is to reduce meniscus extrusion as much as possible [17]. However, meta-analysis on the outcomes of MMPRT repair showed no change in meniscus extrusion following surgery [18]; the correction of meniscal extrusion following repair is debatable and there are only few studies [19,20,21,22] that have investigated the result after MMPRT repair. The aim of our study is to evaluate the effect of a diverse set of factors surrounding MMPRT repair on the correction of meniscal extrusion and functional outcomes. The hypothesis of the study is that the influence of age along with other factors would interplay for good extrusion correction and for superior clinical outcome in degenerative medial meniscal root tears.

Material and methods

This is a retrospective study and enrolled all the patients (n = 72) with degenerative medial meniscus posterior root tear (MMPRT) during Jun 2014 to Aug 2018. The data of the study population were obtained from the Medical Records Department (MRD), the Electronic Medical Registry (EMR) database, Physiotherapy department and the MRI data measurements were done using the Hospital Picture Archiving and Communication System (Medsynapse PACS, v.5.0.1.3, Medsynaptic Pvt Ltd.) in our institution. The Institutional review board for ethical committee approval and written informed consent from all the patients were obtained for this study. Diagnosis of MMPRT was done on the basis of specific MRI findings—the absence of an identifiable meniscus or a high signal that replaced the normal dark meniscal signal (ghost sign) in the sagittal view (of para-median section), a vertical linear defect at the meniscus root in the coronal view, or a radial linear defect at the posterior insertion in the axial view [23]. The inclusion criteria were: (1) an isolated MMPRT with extrusion on MRI in a patient with persistent knee pain following trivial incident, (2) Type 2 MMPRT Laprade classification [24], (3) patients with maximum duration of the symptoms for 6 months, (4) root tear with Kellgren–Lawrence (KL) grade 1 or 2 osteoarthritic changes in X-ray, and (5) patients who had surgical repair with a minimum 2-year follow-up. The exclusion criteria for this study were: (1) patients with Type 1, 3, 4 and 5 MMPRT Laprade classification [24] and irreparable root tears, (2) patients whose MMPRT repair was combined with high tibial osteotomy for varus malalignment greater than 5 degrees, (3) patients with a concomitant ligament injury, (4) root tear with KL grade 3 or 4 osteoarthritic changes in X-ray and (5) chronic root tears with durations more than 6 months. Laprade type 1 tear is partial tear may not need root repair, while other Laprade types of root tears are more complex tears which would require partial meniscectomy/additional procedure and would be the compounding factor for analysing the results hence excluded from the study. Of 72 patients, 12 patients were with other Laprade type tears and associated ligamentous injuries and four patients with gross degenerative irreparable posterior horn tear with higher KL grade osteoarthritis and varus malalignment greater than 5 degrees were excluded from the study. Two patients were lost to follow-up. A total of 54 patients satisfied our inclusion and exclusion criteria and all patients were clinically followed-up for minimum duration of 24 months. The various patient related factors such as age, gender, duration of symptoms, hip–knee–ankle angle on weight-bearing X-rays, KL grade from weight-bearing knee x-ray, International cartilage repair society (ICRS) grading of cartilage status of medial compartment of knee (arthroscopic finding), were correlated to the clinical and radiological outcome. Intra-operative ICRS grading of cartilage damage in the medial compartment was documented in our study during the procedure and we divided into two groups: low grade (0, 1, 2) and high grade (3, 4) cartilage lesion.

Surgical technique

All the patients underwent arthroscopic medial meniscal root repair by trans-tibial suture pull-out technique. Under spinal anaesthesia and tourniquet control knee joint examined through standard anterolateral portal and anteromedial portal. Meniscus posterior horn root tear identified (Fig. 1a) and freshened. Intra-operatively cartilage lesions recognised and classified according to ICRS grading [25]. In 25 patients with fixed varus with narrow medial joint space, percutaneous needle pie crusting of superficial medial collateral ligament (MCL) was necessary for the passage of instruments for repair of the detached root. Posterior root attachment site freshened (adjacent cartilage was denuded) to ensure adequate healing of the root to subchondral bone. ACL tibial guide (Arthrex, Naples, Fl) (Fig. 1d) was placed at anatomical site and 4 mm tunnel drilled from anteromedial proximal tibial surface. (Video 1) Knee Scorpion™ Suture Passer (Arthrex, Naples, Fl) instrument was introduced through the anteromedial portal and passed through the posterior root of meniscus around 5 mm medial to the edge. 0 Fibre wires high strength braided sutures (Fibrewire; Arthrex, Naples, Fl) are then shuttled through the posterior root (Fig. 1e). Two fibre wires were used in all the cases and sutures inserted in cinch fashion. The rationale behind this is, medial fibre wire would pull the root of the meniscus towards the intra-articular tibial tunnel opening, and the lateral fibre wire would compress the medial end of the root onto the denuded cartilage bed. Both the fibre wire would also ensure that an adequate correction of extrusion is also possible. These fibre wires then pulled-out through the tunnel with suture retriever and tied over the suture disc (Video 2) on anteromedial proximal tibia surface, while arthroscopically observing reduction of root to its bed (Fig. 1f). The stability of the repair was assessed during flexion and extension of knee joint. No reverse notch plasty was done in any of the cases. Knee splinted in a brace for about 2 weeks. Postoperatively, toe-touch weight-bearing was allowed for the first-6 weeks. Knee mobilisation was started on postoperative day 2 and progressed to 90° flexion by 4 weeks. Full flexion of knee was achieved by 6 weeks and partial weight-bearing was started after 6 weeks and progressed to full weight-bearing by the end of 8 weeks. Weight-resisted exercise and half squat exercise were started from third month onwards. Patients were allowed to participate in sports, running, squatting for eastern comourd, sitting crosslegged on the floor and other heavy activities, only after 6–8 months of rehabilitation.

Fig. 1
figure 1

a Medial meniscus root tear, b sutures taken with Knee Scorpian instrument, c fiber wire through the meniscus root and cinch-loop typed into the meniscus, d tibial tunnel drilled with ACL jig at near anatomical location, e both the blue and white sutures are shuttled through the tibial tunnel tied over suture disc on the anterior tibial cortex, f final picture after repair

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All the patients were clinically followed-up at regular intervals and functional assessment done using Lysholm score [26] and IKDC score [27] pre-operatively and postoperatively at 6 months, 1 year and yearly until final follow-up. Pre-operative weight-bearing X-ray and alignment X-rays done to evaluate osteoarthritis grade, by KL classification, and hip–knee–ankle angle (HKA) and MRI evaluation was done pre-operatively and at the 6-month follow-up to assess correction of extrusion, healing status, and tunnel position. (Figs. 2, 3, 4). Kaplan et al. [28] has recommended earliest MRI at 4-month follow-up, in his study, and post-operative MRI at 4–6 months would give the earliest evidence of healing status of the repaired meniscal root and extrusion correction. MRI data were studied by two musculoskeletal trained radiologists and interobserver reliability was assessed. Maximum extrusion of meniscus was measured in the mid coronal section of MRI where tibial plateau has widest diameter. Pre-operative and postoperative extrusion of meniscus were measured in same cuts of the coronal section (Fig. 2). Positive correction of extrusion was indicated by lower value of post-operative measurement. From previous studies,  > 3 mm of extrusion was considered pathologic [29], thus when the postoperative extrusion is less than pre-operative extrusion and less than 3 mm it was considered as good correction. Tunnel positioning was also studied on MRI: the centre of the medial meniscus posterior root lies 9.6 mm posterior and 0.7 mm lateral to medial tibial eminence and 8 mm anteromedial to the anterior-most fibres of PCL [30]. If the centre of tibial tunnel was found within 5 mm of the centre of posterior root of the medial meniscus, it was considered an anatomic repair, else it was considered as a non-anatomic repair. Healing of the meniscus was seen in coronal, sagittal and transverse sections. When the continuity of the meniscus was seen in all three sections, repair was considered as healed, if the continuity seen in only one or two sections it was considered as partially healed and no evidence of continuity in all the three sections, the root repair was considered as non-healed (Fig. 4).

Fig. 2
figure 2

a Showing lower limb alignment of 2.20 varus, b showing pre-operative extrusion of 3.21 mm in a mid-coronal section, c arrow clearly shows detachment of posterior root of meniscus, d postoperative x-ray shows suture disc which holds the fiber wire knots over anterior tibial cortex, e postoperative MRI shows suture disc metal artefact and extrusion measurement of 3.93 mm at 6-month follow-up, f postoperative MRI showing complete healing of root of the medial meniscus

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Fig. 3
figure 3

a, b Pre-operative and postoperative MRI showing extrusion measurements and good positive correction of extrusion from 3.67 mm pre-operatively to 2.33 mm postoperatively, c, d healing of the meniscus—continuity of meniscus root in all three sections of MRI (coronal, sagittal and axial sections)

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Fig. 4
figure 4

Postoperative MRI example showing a extrusion of 4.10 mm and b, c, d showing partial healing of root repair that is appears healed in coronal and axial sections; however, hazy at the articular orifice of tibial tunnel in the sagittal section

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Statistical analysis

Statistical analysis was done with R software (version 3.3.1, R Foundation for Statistical Computing, Vienna, Austria). Differences in outcomes by clinical factors were assessed with Student’s t tests and ANOVA. Associations between clinical, structural and functional data were evaluated using a linear multiple regression model, where outcomes of IKDC score, Lysholm score and extrusion correction were regressed against clinical factors of age, extrusion correction and OA grade (via ICRS or KL grading). A post-hoc analysis was used to assess the power of the study. Inter-rater reliability between two raters was assessed, by either Pearson correlation for continuous variables and Cohen’s Kappa for ordinal variables and the value between 0.75 and 1.00 was considered excellent, 0.60–0.74 good, 0.40–0.59 fair, and < 0.40 poor.

Results

Patients had a mean age of 48.5 years (28–68 years) and a mean follow-up of 34.6 months (24–48 months). The study population was predominately female (48 of 54, 89.9%, Table 1). Functional outcomes at final follow-up showed significant improvement in both IKDC (pre-operative 43.40 ± 5.16; post-operative 78.65 ± 5.11, p < 0.001) and Lysholm (pre-operative 65.27 ± 4.28; post-operative 83.16 ± 4.83, p < 0.001) scores. However, correction of extrusion was not significant in our cohort (p > 0.05). 57.4% (31 patients of 54) showed good correction of extrusion (Fig. 5) (in which most of the patients- 25 patients out of 31 i.e. 80.64% were less than 50 years of age) and 3.7% (two patients of total 54) showed no change in extrusion correction (pre-operative extrusion is same as postoperative extrusion). In remaining cohort of patients 38.8% (21 patients of 54) showed increase in extrusion postoperatively (Fig. 2). Patients older than 50 years had an increase in extrusion post-operatively [odds ratio 32.9 (7.0, 155.0), p < 0.001] than patients with age younger than 50 years. A post-hoc analysis showed power to be 0.57 and inter-rater reliability between two raters for extrusion measurement, healing, and tunnel location assessments were to be 0.98, 0.90, and 1.00.

Table 1 Differences in outcomes (IKDC score, Lyshom’s score, meniscal extrusion) by selected factors
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Fig. 5
figure 5

Scatter plot of the relationship between extrusion correction and age, clearly shows the downward trend that is older the patients poorer the correction of the meniscal extrusion

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In multiple regression model, age (β = − 0.37, p = 0.012) and extrusion correction (β = − 2.28, p = 0.043) showed correlation with postoperative IKDC score, however, age, extrusion and KL grade did not show significant correlation with Lysholm’s score. These results infer that, by correcting the influence of KL grade, each additional 10 years of age was associated with in 0.8 mm loss of correction of meniscal extrusion (p < 0.001). In another separate multiple regression models, age (β = − 0.29, p = 0.024), extrusion correction (β = − 3.18, p = 0.005) and ICRS grade (β = − 2.21, p = 0.020), all the three factors were correlated with improvements in IKDC scores; however, ICRS grade (β = − 2.77, p < 0.001) was correlating with improvements in Lysholm scores but age and extrusion were not correlating with lysholms score. These results infer that, each grade of ICRS was correlated with a 0.25 mm (p = 0.031) loss of correction and each additional 10 years of age was correlated with 0.7 mm loss of extrusion correction (p < 0.001).

Duration of symptoms, sex difference was not significantly correlated with IKDC score, Lysholm score and correction of extrusion (Table 1). Patients with knee varus less than 2.5 degrees showed significant improvement in Lysholm score (p = 0.036) and correction of extrusion (p = 0.002) compared to those with varus greater than 2.5 degrees.

41 patients (75%) showed healed meniscus in all the three MRI sections, 9 (16.6%) showed partially healed meniscus, that is healing in at least one MRI section (either coronal/sagittal/axial sections), and 4 (7.4%) showed non-healed meniscus at the 6-month follow-up. Healing status of root repair was not significantly associated with IKDC or Lyshom’s scores (Table 1). However, patients with healed root repair (0.63 ± 0.97 mm) and partially healed repairs (0.59 ± 1.03 mm) had better extrusion correction than those with non-healed repairs (− 1.25 ± 0.89 mm, p < 0.001).

MRI evaluation for tunnel location showed 46 patients had a tunnel within anatomical zone of native meniscal root and eight patients had non-anatomical root repair. Tunnel placement was not significantly associated with IKDC or Lysholm scores. However, patients with anatomic tunnel placement (0.45 ± 1.08 mm) had greater extrusion correction and good healing that those without (− 0.63 ± 1.15 mm, p < 0.001, Table 1).

Discussion

The most important finding of this study is younger patients, with low grade cartilage damage (ICRS 1, 2), lower KL grade 1, 2, alignment (< 2.50), healed meniscus with anatomical tunnel placement showed good correction of meniscal extrusion. Other clinical factors did not show significant correlation. MMPRT is identified in up to 10% of patients who undergo knee arthroscopy [7] with even higher rates in the Asian population [31]. Root avulsions may lead to a sudden sharp pain and distress, during day-to-day activities. Lee et al. found that pain on full flexion was the most frequent clinical manifestation of MMPRT [23]. In our study, MMPRT occurred in middle aged adults (especially females) who heard a sudden catching pain or a sharp snap/pop in their knees during descending stairs, while boarding a high step in a bus or autorickshaw or while walking on a slippery surface. Most of the patients in our study presented with the complaints of knee pain, during descending stairs or while getting up from a squatting position. Sitting on the floor with crossed leg position is a routine practice in the Asian population to eat meals and root tears are common in these position or while getting up from kneeling or squatting position [5].

Root tear may lead to increased contact pressure in the joint and arthroscopic repair has been shown to restore the peak contact pressure to physiologic levels [4, 32, 33]. Various repair techniques have been described in literature, including trans-tibial tunnel suture pull-out repair, all-inside meniscal root repair, suture anchor repair and side-to-side suture repair [15, 34, 35]. All these techniques have reported good results but clinical data is limited and, in most of the studies, the trans-tibial tunnel suture pull-out technique has been used. In a systematic review by Feucht et al. on the pull-out technique, mean Lysholm score improved from 52.4 to 85.9 and mean IKDC score improved from 47.3 to 81.8 after surgery [36].In our study, pull-out fixation showed significantly improved clinical scores at the final follow-up compared with pre-operative scores, which is consistent with previous studies [15].

Time to surgery has not been considered by others authors, therefore, its implication on repair is unknown. Longest duration of presentation in our series is 6 months from the onset of symptoms. Duration of symptoms or the duration since injury may affect the outcome and extrusion correction due to plastic deformation and irreversible meniscus extrusion. However, we found no significant association between this and meniscus extrusion nor functional scores up to 6 months.

The age of patients in our study ranged from 28 to 68 years with a median age of 50 years. Laprade et al. [37] in their study had divided their patient cohort into two age groups (< 50 vs ≥ 50 years) and concluded that there was no difference in functional outcome between groups but there was an increased meniscal extrusion in patients in the higher age group. In our study, age was a major factor, significantly correlated with correction of extrusion, suggesting that chances of correction of the meniscus extrusion decreases in elderly patient. Further, negative correction of extrusion (increased extrusion) was significantly more in patients aged 50 years and older. Chung et al. [18] observed similar results, with patients in their increased-extrusion group having greater ages (Mean age- 57.7 ± 7.2 years) compared to the decreased-extrusion group (positive correction) after MMPRT repair, but their results were not statistically significant.

Patient population in our study consisted of 48 females (89.9%) and six male patients which is consistent with distribution seen in other studies [38, 39]. However, neither functional outcomes (Lysholm score and IKDC score) nor correction of meniscal extrusion were found to be significantly different between genders. This predilection for females (89.9%) and cultural habit of Asian population for root tears has not been reported in literature.

In our study, alignment of the limb was measured by HKA angle on weight-bearing X-rays and we divided patients into two groups: varus less than 2.50 degrees or varus between 2.50 and 50 degrees. We found that there was a significant association between alignment and Lysholm score and meniscus extrusion, which implies that patients with lower varus are more likely to have greater extrusion correction following repair. Greater varus can lead to a tighter medial joint space and a non-anatomical repair, thus would yield inferior results as seen in this study. Moon et al. [22] and Ahn et al. [13] had concluded that varus greater than 5° is associated with inferior clinical outcome after meniscus root repair alone and they advised corrective osteotomy along with the repair—we extend this with observations in a similar vein in patients with 2.5–50 degrees of varus.

In our study, functional outcome (Lysholm score) and extrusion correction were found to be significantly associated with ICRS grading of cartilage in medial compartment, with better outcomes in patients with low grade cartilage lesion. Moon et al. [22] also concluded that higher grade cartilage damage is associated with poor functional outcome.

Meniscus extrusion is a consistent MRI finding in patients with MMPRT. Laprade et al. [37] concluded that decreased meniscus extrusion after repair leads to more favourable clinical outcomes as compare to those with increased meniscus extrusion. In our study, meniscus extrusion was found to be decreased (correction of extrusion) in 57% of patients with a 1.08 mm mean decrease in extrusion. However, scores in patients with positive extrusion correction (Lysholm score- 85.4 ± 4.07, IKDC score- 80.4 ± 6.54) are not significantly different compared to patients with increased extrusion (Lysholm score- 83.5 ± 4.03, IKDC score- 79.2 ± 6.69). Moon et al. [22] found that there was increased meniscus extrusion postoperatively in 74% of their patients and correction of extrusion (postoperative decrease in extrusion) in only 26% of patients [22]. Chung et al. [18] also found increased extrusion of meniscus in 58% of patients and, in the minority of patients with positive extrusion correction, the amount of the extrusion correction was small. This may be due to the chronic plastic deformity of meniscus after root tear [37, 40]. On contrary, Kim et al. [20], Lee et al. [41] and Jung et al. [42] showed positive mean correction of extrusion of the meniscus after repair, but only Kim et al. [20] had statistically significant mean correction of extrusion in their patient cohort. A meta-analysis on the outcomes of MMPRT repair showed no change in meniscus extrusion after repair [18]. Thus, a significant correction of extrusion is determinable to prevent tibiofemoral contact, restore meniscal function (hoop stress) and eventually osteoarthritis. However, short-term functional outcome is independent of extrusion correction as seen in our study and long-term follow-up is required to know the implications of increased extrusion. Daney et al. from his cadaveric study has found out that anatomic repair augmentation with a centralization suture resulted in significantly reduced extrusion and suggested that it could be beneficial additional procedure that can be clinically implimented for chronic repair and could yield better long-term prognosis [43]. However, he has not given the cut-off value (extrusion distance) for the need for centralization sutures as it was a cadaveric study. There is no available consensus for the indications of this procedure and no quantification value for extrusion distance that needs this additional procedure. Pre-operative meniscal extrusion greater than 3 mm was considered significant [29] and suggested all-inside centralization sutures by Chernchujit et al. [44]. In our study, none of the patient had this additional procedure along with root repair. Further, the high-risk patients can be considered for additional auxiliary procedures like centralization sutures for better correction of extrusion.

Tibial tunnel placement was assessed in postoperative MRI. Eight patients had non-anatomical placement of tunnel and 46 patients had anatomical placement of tunnel. As placement of the tunnel depends on the location of tear at the posterior root, a radial tear at 1 cm from root attachment requires tunnel placement more medially as compared to tears at the root attachment. Also, non-anatomical tunnels were seen in more varus knees. We found no significant difference in anatomical versus non-anatomical repair with respect to functional scores. However, anatomic tunnels had significantly greater correction of the extrusion; this the tunnel opening is closer to native root attachment in anatomic repair and, therefore, we postulate that would yield better healing at the repair site and, hence, better correction of extrusion. This also supported by results from Laprade et al. [45] where they postulate that non-anatomic tunnel placement cannot restore the normal contact area and contract pressure [21] as a possible reason for poorer extrusion correction.

Healing of the meniscus was assessed in postoperative MRI. 41 patients (75%) had healed, nine patients (17%) had partially healed andfour4 patients (7%) had non-healed meniscus root. Non-healing and partially healed meniscus were predominantly found in older patients and non-anatomic repairs. Moon et al. [22] found good healing in 28 out of 31 patients on postoperative MRI. Ahn et al. [46] performed second-look arthroscopies in nine patients after a posterior lateral meniscal root repair and found complete healing in eight patients. Seo et al. [47] performed second-look arthroscopies in 11 patients, 10–22 months following pull-out repair of posterior medial root tears and found no patients with complete healing of the posterior medial meniscal root. In a systemic review [36], 62% patients had complete healing, partial in 34%, and failed in 3% of arthroscopic medial meniscal root repair, which is similar to our results (Table 2). Further, In challenging scenarios like chronic meniscal root tears with > 5–7 mm retraction, a complex radial tear in posterior horn, long-standing degenerated root stump, failed anatomical root repairs and in revision root repair for non-healed root cases, root reconstruction with Gracilis autograft is a valuable salvage technique that can be considered. This bailout technique was popularised by Lee et al. [48] in 2017.

Table 2 Comparison of correction of extrusion, mean age, healing status and location of tunnel status of our study with others studies
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There was no significant correlation between extrusion correction and the functional outcomes (Lysholm and IKDC score) in our study. Meniscal root repair gives better functional results irrespective of reduction of meniscus extrusion according to most of the studies. Preliminary studies have reported improvement in function, pain, and objective measures [19, 20] following the repair. Various biomechanical studies have shown that repaired meniscus root restored peak contact pressures close to normal [23]. Thus, the ultimate goal in MMPRT surgeries are to resort joint mechanics and retard osteoarthritis pathways. However, it is also possible that the repair of the meniscus and restoration of joint mechanics can also prevent further extrusion of the meniscus, leading to better functional outcomes, as postulated by previous authors [49], though our results do not support this hypothesis. Various studies have investigated the change in meniscus extrusion after repair and its implication on functional outcomes and reported mixed results [9, 18, 46]. As described by Chung et al. [18], MMPRT fixation was an effective method for maintaining meniscal hoop tension and delaying the progression of arthritis, though it did not reduce meniscus extrusion completely or prevent the progression of arthritis completely [18]. So, though meniscus extrusion is increased in our study, it may not relate to the actual extrusion at the time of weight-bearing and the meniscus may still be able to withstand hoop stress in spite of increased extrusion. From our study, it’s evident that patients with age beyond 50 years, higher varus alignment, and higher ICRS grade, non-anatomical tunnel, non-healed meniscus, showed poor correction and outcome and can be termed as high-risk patients for poor extrusion correction.

Limitations

There are limitations to our study like this is a retrospective study design. Prospective randomised study would be the way forward to compare the extent of progression of extrusion in meniscal repair and non-operative managed patients in older patients. Further, MRI was done at 6 months postoperatively, but extrusion of the meniscus may progress after this period as well, so it is difficult to correlate the extrusion at such an early time point with the later functional outcomes. Healing of the meniscus, as seen in MRI, at 6 months may similarly not be representative of healing at later points in the follow-up period. Moreover, we followed patients at least to 2 years post-operatively, though progression to osteoarthritis cannot be definitely observed in this short period and further long-term study is needed to draw direct linkages to the onset and progress of arthritis.

Conclusion

Of all the factors, patients younger than 50 years with low grade cartilage damage (ICRS 1, 2), and alignment less than 2.50 varus have better functional outcomes and extrusion correction after the repair. Correction of extrusion/progression of extrusion did not influence the clinical outcome at the short term. The progression of meniscal extrusion is inevitable even after successful repair in elderly patient and high-risk patients.