Osteoarthritis Progression After Medial Meniscus Posterior Root Repair: An Analysis of Surgical Timing and Baseline Degenerative Severity

Abstract

Background:

Medial meniscus posterior root tears (MMPRTs) disrupt hoop stress transmission, leading to increased contact pressures, extrusion, and accelerated medial compartment osteoarthritis (OA). Although early surgical repair is widely recommended, it remains unclear whether surgical timing independently influences long-term radiographic outcomes after root repair.

Purpose:

To compare radiographic OA progression after acute (≤3 months from symptom onset) versus chronic (>3 months) MMPRT repair and to determine whether surgical timing independently predicts Kellgren-Lawrence (KL) grade progression after adjusting for baseline degenerative severity.

Study Design:

Cohort study; Level of evidence, 3.

Methods:

Patients undergoing isolated arthroscopic transtibial pullout repair for MMPRT between 2016 and 2023 were retrospectively reviewed. Inclusion required preoperative magnetic resonance imaging (MRI) and 2-year postoperative weightbearing radiographs. Patients were categorized as acute or chronic based on time from symptom onset to surgery, rather than confirmed time of tear occurrence. Primary outcome was change in KL grade (ΔKL). Secondary variables included preoperative meniscal extrusion percentage, joint space width, MRI diagnostic signs, mechanical alignment, and International Knee Documentation Committee (IKDC) scores. Multivariable linear regression was used to identify independent predictors of ΔKL progression.

Results:

In total, 61 patients met the inclusion criteria (acute: 30; chronic: 31). The chronic cohort demonstrated greater unadjusted KL progression (mean ΔKL: 0.65 vs 0.40; P = .049) and higher preoperative meniscal extrusion (47.9% vs 38.7%; P = .030). Multivariable analysis, however, showed that surgical timing (acute vs chronic) was not an independent predictor of ΔKL progression (P = .31). Instead, meniscal extrusion (β = 0.013, P = .023) and preoperative joint space width (β = −0.194, P = .051) were the strongest predictors of radiographic worsening. Joint space narrowing, MRI signs, mechanical alignment, and postoperative IKDC scores were comparable between groups.

Conclusion:

Although patients undergoing chronic MMPRT repair demonstrated greater unadjusted radiographic progression compared with those treated acutely, this effect does not persist after controlling for baseline degenerative severity. Osteoarthritis progression after root repair is primarily associated with the preoperative degenerative burden—particularly meniscal extrusion—rather than surgical timing itself. Early diagnosis and referral remain important because delayed presentation is associated with more advanced degeneration at the time of surgery.

Keywords

medial meniscus root tear posterior root repair meniscal extrusion Kellgren-Lawrence grade osteoarthritis progression surgical timing knee biomechanics

The structural and functional integrity of the meniscus is critical for maintaining knee joint stability, congruity, and proper load distribution.^2,25 The medial meniscus root plays a key biomechanical role by converting axial loads into hoop stresses through its firm attachment to the tibial plateau.^2,25,47 Disruption of this attachment—referred to as a medial meniscus posterior root tear (MMPRT), defined as a radial tear within 1 cm of the posterior root insertion or an avulsion of the root itself—leads to loss of hoop tension, meniscal extrusion, altered tibiofemoral contact mechanics, and increased medial compartment pressures comparable to those observed following total meniscectomy.^5,8,24 These injuries contribute to rapid cartilage deterioration and represent a significant cause of disability, accounting for 10% to 21% of all meniscal tears and affecting nearly 100,000 individuals annually.⁸ Clinically, MMPRTs are increasingly recognized as a major contributor to early-onset medial compartment osteoarthritis (OA).^8,11,22 They are often degenerative in nature,¹ typically presenting in middle-aged or older adults, and may be precipitated by even minor trauma.⁵⁰

Given their accelerated degenerative potential, early arthroscopic repair is generally recommended for appropriately selected patients to restore native biomechanics and limit further structural deterioration.²⁰ However, many patients present only after symptoms have persisted for weeks or months, raising concerns about whether delayed (chronic) repair is associated with less favorable biological and structural conditions for healing or leads to inferior long-term joint preservation.³¹ During this chronic phase, progressive meniscal extrusion and joint space narrowing may occur, potentially diminishing the reparability of the root and predisposing patients to more advanced OA at the time of surgery.

A growing body of literature suggests that delayed intervention is associated with greater meniscal extrusion and poorer clinical or radiographic parameters.^27,40 As such, early repair is often advocated. However, most existing studies have focused on medial meniscus extrusion (MME) as a surrogate marker of degenerative change rather than evaluating OA progression directly using standardized radiographic criteria.^15,45,48 Despite increasing clinical emphasis on timely intervention, no consensus exists regarding the precise time threshold that defines “acute” versus “chronic” repair. Moreover, the extent to which surgical timing independently influences radiographic OA progression—separate from the degenerative burden already present at the time of surgery—remains insufficiently understood.

The primary purpose of this study was to evaluate the association between surgical timing (acute vs chronic) and radiographic progression of knee OA following arthroscopic repair of MMPRTs.

The secondary purpose was to determine whether observed differences in OA progression were attributable to surgical timing itself or to the baseline degenerative severity present at the time of surgery.

We hypothesized that patients undergoing chronic repair would exhibit greater radiographic progression of OA and that this difference would be associated with greater baseline degenerative burden rather than surgical delay alone.

Methods

Study Design

This study was approved as exempt by the Institutional Review Board of Rush University Medical Center (ORA #23083005-IRB01). Patients who underwent arthroscopic transtibial pullout repair for MMPRTs between January 2016 and January 2023 were retrospectively identified from institutional databases. Although patients were treated at multiple centers by different orthopaedic surgeons, all procedures were performed using the same standardized arthroscopic transtibial pullout technique. All preoperative and postoperative imaging was reviewed centrally, and radiographic measurements were conducted by a single blinded evaluator to ensure consistency across institutions. Interobserver reliability was additionally assessed in a subset of cases by independent evaluation performed by a second blinded observer. Only patients who underwent isolated root repair procedures were included. Individuals undergoing additional procedures such as osteotomy, ligament reconstruction, cartilage restoration, or lateral meniscus repair were excluded.

Patients were included if they had preoperative magnetic resonance imaging (MRI), standardized preoperative and 2-year postoperative knee radiographs, and a clearly documented time of symptom onset based on either patient-reported history or identifiable injury events. Patients were categorized into acute (≤3 months from symptom onset) and chronic (>3 months) groups according to the timing of surgical intervention.

Power Analysis

In this study, a power analysis was conducted to determine the required sample size for detecting a clinically meaningful difference in radiographic OA progression, defined as the magnitude of change in Kellgren-Lawrence grade (ΔKL), between acute and chronic meniscus root tear groups. Since no previous studies with a similar design were available, an effect size of 0.8 (large effect size, Cohen's d) was assumed based on the expectation of a clinically significant difference. The analysis was performed using G*Power (latest version 3.1.9.7, University of Düsseldorf, Germany). The parameters were set as follows: significance level (α) = .05, statistical power (1 –β) = 0.80, and equal group allocation (allocation ratio = 1). The calculations determined that a minimum of 26 patients per group (a total of 52 patients) would be required to achieve sufficient power (actual power = 0.807).

Study Population and Data Analysis

Demographic and clinical variables—including age, sex, height, body mass index (BMI), laterality, and comorbidities—were retrospectively collected. Prospectively collected International Knee Documentation Committee (IKDC) scores were available at a minimum of 2-year follow-up.

Radiographic assessment used standardized standing anteroposterior knee radiographs to determine Kellgren-Lawrence (KL) grades preoperatively and at 2 years. Coronal alignment was evaluated using full-length standing lower-extremity radiographs. The hip-knee-ankle (HKA) angle was defined as the angle between the femoral and tibial mechanical axes (varus positive, valgus negative). The weightbearing line ratio was calculated by dividing the distance from the medial tibial edge to the intersection of the mechanical axis by the total tibial plateau width.

MRI evaluation included measurement of MME and medial meniscus extrusion ratio (MMER) following the method described by Costa et al¹⁶ and Farivar et al.²¹ MME was measured on the coronal slice corresponding to the sagittal midpoint of the medial femoral condyle, and MMER was calculated as the ratio of extrusion distance to total meniscal width. The presence of established MRI signs associated with medial meniscus posterior root tears was recorded, including the ghost sign (defined as loss or marked attenuation of the posterior horn on sagittal images) and the truncation sign (defined as an abrupt absence of the posterior root on coronal images), according to previously described criteria.¹² Preoperative MRI was also used to qualitatively assess articular cartilage morphology and bone marrow edema; however, MRI-based cartilage or bone marrow edema severity was not graded using validated, standardized scoring systems. All imaging measurements were performed by a single blinded evaluator and repeated twice with a minimum 3-week interval to assess intraobserver reliability.

Interobserver reliability was assessed in a subset of 8 knees independently evaluated by a second blinded observer. Agreement for KL grading and joint space width (JSW) measurements was quantified using a 2-way random-effects, absolute-agreement intraclass correlation coefficient (ICC 2,1). Because postoperative KL grades showed no variability across patients (all KL = 2 for both observers), ICC estimation was not applicable for postoperative KL grading. Preoperative KL grading demonstrated perfect agreement (ICC = 1.00), while JSW measurements demonstrated excellent agreement both preoperatively (ICC = 0.98) and postoperatively (ICC = 0.91).

Surgical Technique

The indication for arthroscopic transtibial pullout repair of MMPRT included the following: (1) presence of an isolated MMPRT confirmed arthroscopically; (2) absence of concomitant ligamentous or meniscal injuries; (3) mechanical axis alignment showing nonsevere varus deformity (HKA angle ≤10°), with patients with severe varus malalignment not considered candidates for isolated root repair; (4) compliance with the postoperative rehabilitation protocol; and (5) availability of at least 2 years of postoperative follow-up. There was no upper age limit for surgical candidacy. Patients who had grade 4 cartilage degeneration according to the International Cartilage Repair Society classification during diagnostic arthroscopy were excluded from the final analysis to avoid confounding by advanced, end-stage cartilage degeneration, although surgery was still performed. Although intraoperative chondral surfaces were assessed during diagnostic arthroscopy, these findings were not included as independent variables in the analysis because they were not systematically graded or recorded in a standardized manner across all centers.

All procedures were performed arthroscopically with the patient in the supine position. Standard high anterolateral and anteromedial portals were established. Diagnostic arthroscopy was carried out to assess all compartments, with confirmation of the MMPRT made in the medial compartment. The tibial root footprint was gently debrided with a shaver to expose a bleeding bony bed.⁹

Through the anteromedial portal, according to the 2-simple sutures technique, 2 nonabsorbable sutures (eg, No. 2 FiberWire [Arthrex]/tape or equivalent) were passed through the posterior horn of the medial meniscus approximately 3 to 5 mm from the torn edge using a suture-passing device. The same 2-simple suture configuration was used in all cases without variation.

A tibial tunnel was created using a root tibial drill guide directed toward the anatomic insertion site of the medial meniscus posterior root, just anterior to the posterior cruciate ligament insertion. The tibial footprint was decorticated with an arthroscopic rasp to enhance healing potential. The previously placed sutures were retrieved through the tunnel using a wire loop and brought out to the anteromedial tibial cortex.

Fixation was performed using a polyether ether ketone anchor placed at the tibial cortex, securing both suture ends under appropriate tension to reduce the root anatomically onto the prepared bony bed (Figure 1).

Figure 1.

Illustration of surgical technique and arthroscopic view of root repair. The arthroscopic views demonstrate key steps of the repair technique. The torn posterior root footprint is identified and prepared. Nonabsorbable sutures are passed through the posterior horn of the medial meniscus using a suture-passing device. The sutures are retrieved through the transtibial tunnel, allowing reduction of the meniscal root to its anatomic tibial insertion site. Final fixation is achieved with cortical anchor fixation, restoring tension and anatomic positioning of the root.

All patients followed a standardized rehabilitation protocol. For the first 6 weeks, patients were nonweightbearing and used a hinged knee brace locked in full extension during ambulation and sleep. Range of motion exercises were initiated immediately postoperatively, limited to 0° to 90°, with emphasis on achieving full extension. At 6 weeks, partial weightbearing was allowed and gradually progressed to full weightbearing as tolerated, with transition to an unloader brace maintained until 6 months. Closed-chain strengthening, proprioception training, and stationary cycling were initiated at 8 to 12 weeks. Return to running and sport-specific activities was permitted no earlier than 3 to 4 months postoperatively, following functional criteria. Deep knee flexion (eg, squatting) was avoided for 24 weeks postoperatively and discouraged thereafter.

Statistical Analysis

All statistical analyses were performed using Python (Python Software Foundation). Descriptive statistics were reported as means and standard deviations for continuous variables and as frequencies and percentages for categorical variables. Normality of distribution was assessed using the Shapiro-Wilk test. Because most continuous variables were not normally distributed, comparisons between acute and chronic cohorts were performed using the Mann-Whitney U test⁴⁶ for continuous variables and chi-square²⁶ analysis for categorical variables, including the presence of ghost and truncation signs. Radiographic OA progression was evaluated both as a continuous variable—calculated as the change in KL grade from preoperative to postoperative radiographs (ΔKL) to reflect the magnitude of change—and as a categorical variable, defined as progression of at least 1 KL grade, to reflect clinically meaningful radiographic worsening. To account for baseline differences between groups, multivariable regression models were constructed. A multiple linear regression model was used to evaluate independent predictors of continuous KL grade progression (ΔKL), including chronicity, age, sex, BMI, preoperative KL grade, preoperative JSW, meniscal extrusion percentage, and mechanical alignment. A binary logistic regression model was used to evaluate predictors of categorical KL progression (≥1 grade). Regression coefficients, odds ratios (ORs), 95% confidence intervals, and P values were reported.

Continuous variables are presented unadjusted and adjusted to allow comparison of crude versus confounder-controlled results. Statistical significance was set at P < .05 for all analyses. Graphical illustrations were generated to visualize the distribution of key study variables.

Results

Study Cohort

Of the 172 patients initially identified, 6 were excluded because of insufficient documentation of symptom onset. Among the remaining patients, 165 had accessible preoperative imaging, and 7 were excluded because their files were missing or nondigitized. Only 61 patients had standardized postoperative radiographs with a minimum 2-year follow-up and were therefore included in the final analysis. Patients without standardized 2-year postoperative radiographs were excluded from the analysis; information regarding subsequent conversion to total knee arthroplasty was not consistently available for these individuals. Of these, 30 underwent acute repair (≤3 months), and 31 underwent chronic repair (>3 months). Patients were not matched between groups; group sizes reflect the available cohort meeting inclusion criteria (Figure 2).

Figure 2.

Flowchart of patient inclusion in the present study. MMPRT, medial meniscus posterior root tear.

The mean patient age was 58.9 years (range, 43.4-74.9 years), and the mean BMI was 31.6 kg/m² (range, 22.3-44.8 kg/m²). Women comprised 73.8% (n = 45) of the cohort. Laterality was evenly distributed (51% left, 49% right). Comorbidities included diabetes mellitus in 14.8% and hypertension in 36.1% of patients.

Baseline Radiographic and MRI Characteristics

Significant baseline differences were observed between the 2 cohorts. Patients undergoing chronic repair demonstrated greater medial meniscus extrusion at presentation (47.9% vs 38.7%, P = .03), narrower preoperative JSW (4.26 mm vs 5.03 mm, P = .03), and a higher prevalence of the truncation sign (80.6% vs 50.0%, P = .025). A trend toward higher preoperative KL grade was also noted in the chronic group (2.16 vs 1.90, P = .08). In contrast, the prevalence of the ghost sign (P≥ .999) and mechanical axis alignment (P = .995) did not differ significantly between groups. Collectively, these findings indicate that the chronic cohort presented with a substantially greater baseline degenerative burden. Table 1 summarizes baseline demographics.

Table 1

Baseline Demographic, Radiographic, and Clinical Characteristics of Patients Undergoing Acute Versus Chronic Medial Meniscus Root Repair ^a

Variable	Acute Repair	Chronic Repair	P Value
Number of patients	30	31	—
Mean age, y	58.81	59.04	.868
Age range, y	43.4-74.9	48.1-72.3	—
Mean BMI, kg/m²	30.4	32.72	.108
BMI range, kg/m²	22.3-43	22.5-44.8	—
Female, %	56.7	90.3	.007
Male, %	43.3	9.7	.007
Left knee, %	53.3	48.4	.896
Right knee, %	46.7	51.6	.896
Preoperative KL grade	1.90 ± 0.61	2.16 ± 0.52	.080
Postoperative KL grade	2.30 ± 0.70	2.81 ± 0.79	—
Mean KL grade change	0.40	0.65	.049
Preoperative joint space, mm	5.0 ± 1.3	4.3 ± 1.0	.028
Postoperative joint space, mm	4.3 ± 1.4	3.3 ± 1.1	—
Joint space change, mm	0.7	1.0	.160
Medial meniscal extrusion, %	38.66 ± 16.30	47.95 ± 14.86	.030
Ghost sign presence, %	53.3	54.9	≥.999
Truncation sign presence, %	50.0	80.6	.025
Mechanical axis, deg	181.5 ± 3.6	181.6 ± 5.5	.995
Preoperative IKDC score	34.6 ± 16.3	31.9 ± 14.9	.480
Postoperative IKDC score	63.8 ± 22.6	60.8 ± 22.9	.480
IKDC change	+35.6	+25.2	.110

Values are presented as mean ± SD unless otherwise indicated. BMI, body mass index; IKDC, International Knee Documentation Committee; KL, Kellgren-Lawrence.

Unadjusted Osteoarthritis Progression

Unadjusted analyses demonstrated greater radiographic progression in the chronic cohort, with a mean increase in KL grade of 0.65 ± 0.61 compared with 0.40 ± 0.72 in the acute cohort (P = .049) (Figure 3). Similarly, categorical progression—defined as an increase of at least 1 KL grade—occurred in 45.2% of chronic patients versus 30.0% of acute patients. Although joint space narrowing was slightly more pronounced in the chronic cohort (1.0 mm vs 0.7 mm), this difference did not reach statistical significance (P = .16).

Figure 3.

Raincloud-style visualization of radiographic osteoarthritis progression (change in Kellgren-Lawrence grade [ΔKL]) following acute versus chronic medial meniscus posterior root repair. Each raincloud plot displays individual patient data points (jittered dots), a kernel density distribution illustrating the overall shape of ΔKL values, and an embedded boxplot summarizing the median and interquartile range for each group. The figure illustrates the distribution and variability of unadjusted ΔKL progression, showing a tendency toward greater radiographic progression in the chronic cohort compared with the acute cohort.

Multivariable Linear Regression: Predictors of Continuous KL Progression

To account for baseline differences between groups, a multiple linear regression model was constructed incorporating chronicity, age, sex, BMI, preoperative KL grade, preoperative JSW, meniscal extrusion percentage, and mechanical axis alignment (Table 2). The model demonstrated good overall fit (R² = 0.453; P = .0045). Higher BMI and greater preoperative meniscal extrusion percentage were significant independent predictors of greater KL progression (BMI: β = 0.045, P = .005; extrusion: β = 0.013, P = .023), whereas narrower preoperative joint space showed a borderline association (β = −0.194, P = .051) (Appendix Figure 1). Preoperative KL grade demonstrated an inverse association consistent with subsequent KL progression: a ceiling effect (β = −0.54, P = .010), whereby higher baseline KL grades limit the potential for further radiographic worsening. In contrast, chronicity did not independently predict KL progression after adjustment for baseline degenerative factors (β = −0.183, P = .31).

Table 2

Multivariable Linear Regression Predicting Change in Kellgren-Lawrence Grade (ΔKL)

Predictor	β Coefficient (95% CI)	P Value
Chronicity >3 months (vs ≤3 months)	0.183 (–0.180 to 0.545)	.313
Age at surgery, y	0.001 (–0.022 to 0.024)	.925
Male sex (vs female)	−0.080 (–0.529 to 0.369)	.720
Body mass index, kg/m²	0.045 (0.014 to 0.075)	.005
Preoperative Kellgren-Lawrence grade	−0.538 (–0.939 to −0.137)	.010
Preoperative joint space width, mm	−0.194 (–0.388 to 0.001)	.051
Meniscal extrusion, %	0.013 (0.002 to 0.023)	.023
Mechanical axis, deg	0.014 (–0.022 to 0.051)	.428

Multivariable Logistic Regression: Predictors of ≥1 KL Grade Progression

Because radiographic OA progression was evaluated as both continuous (ΔKL) and categorical (≥1 grade progression) outcomes, complementary linear and logistic regression models were performed.

Logistic regression analysis (pseudo-R² = 0.46; model P < .001) demonstrated that meniscal extrusion percentage was a significant independent predictor of categorical KL progression (OR = 1.09, P = .026). Preoperative JSW was also associated with the likelihood of progression, with narrower joint spaces predicting a higher risk (OR = 0.18, P = .048). Chronicity (>3 months) exhibited only a trend toward significance (OR = 8.46, P = .065) and did not emerge as an independent determinant after adjustment. Preoperative KL grade was significantly associated with progression, consistent with a ceiling effect (OR = 0.01, P = .010), whereas BMI showed a borderline association (OR = 1.21, P = .055) (Appendix Table 1).

IKDC Functional Outcomes

Pre- and postoperative IKDC scores were available for 27 patients in the acute cohort (90% compliance) and 26 patients in the chronic cohort (83.9% compliance). Although both groups demonstrated substantial clinical improvement from baseline, the magnitude of improvement did not differ significantly between the 2 groups. The acute cohort improved by an average of 35.6 ± 14.6 points, whereas the chronic cohort improved by 25.2 ± 23.9 points (P = .11).

Discussion

The principal finding of this study is that although the chronic cohort exhibited greater unadjusted progression in KL grade following medial meniscus posterior root repair, this association was no longer significant after adjusting for key baseline degenerative factors, particularly medial meniscus extrusion and preoperative JSW. These results indicate that the worse radiographic outcomes observed in patients treated later in their disease course are not independently associated with surgical delay alone but with greater baseline degenerative severity present at the time of surgery. In this context, chronicity functions less as an independent risk factor and more as a surrogate marker of advanced structural degeneration at the time of surgery.

The biomechanical rationale underlying this interpretation is well established. Disruption of the posterior root compromises hoop tension, leading to increased medial compartment contact pressures comparable to those observed after total meniscectomy.^10,41,42 This altered environment accelerates chondral degeneration and promotes meniscal extrusion, which further reduces the meniscus's ability to transmit load effectively.^4,6,17,28,44 Early root repair aims to restore this load-sharing mechanism before extrusion, capsular scarring, and degenerative remodeling become irreversible.^32,33,57 Our findings, however, suggest that once the degenerative cascade has progressed—marked by greater extrusion and narrowing of the joint space—the structural environment at the time of surgery may be less favorable for optimal repair, regardless of whether the root is anatomically reduced.

A critical observation in the present cohort was that chronic presentations exhibited significantly greater meniscal extrusion and narrower JSW at baseline. Prior studies have suggested that meniscal extrusion and root tears exist in a bidirectional relationship and that the sequence of pathology is not always clear.^10,16,19,29 However, evidence consistently supports that meniscal extrusion is more frequently observed in chronic presentations, although the temporal sequence and causality remain uncertain, and that chronic cases are commonly associated with capsular adhesion, scar maturation, and morphological meniscal changes that may limit the potential for complete reduction.^18,56 Our regression analyses reinforce this understanding: meniscal extrusion—not chronicity—was the independent predictor of KL progression. This suggests that the degenerative burden present at the time of surgery, rather than the time interval itself, dictates long-term structural outcomes.^38,39 In this framework, surgical timing appears to be associated with differences in degenerative severity at presentation rather than serving as an independent predictor of radiographic progression. Higher BMI also emerged as an independent predictor of radiographic progression, underscoring the contribution of systemic mechanical loading to degenerative joint changes following root repair.

Several studies have reported temporal thresholds—approximately 12 to 16 weeks—beyond which extrusion becomes significantly more pronounced and less reversible.^15,48 Moon et al⁴⁸ identified a 13-week inflection point, while Kamatsuki et al³⁴ demonstrated reduced repair effectiveness beyond 112 days. Chung et al¹⁵ further noted that exceeding this acute period accelerates OA progression. Our findings are consistent with the biological implications of these studies but offer a distinct perspective: rather than timing exerting a direct causal effect, it appears to operate as the period during which degenerative changes accumulate. Thus, early repair remains important—not because time itself independently alters outcomes but because timely intervention intercepts the biological cascade before irreversible damage occurs.

Radiographically, both groups demonstrated progression in KL grade and reduction in JSW over the 2-year follow-up, consistent with evidence that root repair cannot fully halt OA progression.^{20,35,36,48,55} Interestingly, KL progression differed between groups while joint space narrowing did not. This discrepancy underscores the multifactorial nature of KL grading, which incorporates osteophyte formation, subchondral sclerosis, and overall structural morphology in addition to JSW.^7,23,58 Thus, KL grade may be more sensitive than JSW for detecting early degenerative changes in patients with MMPRTs, particularly when extrusion and cartilage remodeling coexist.³⁷

Functional improvement, as measured by IKDC scores, was substantial and comparable between groups, consistent with prior observations that subjective recovery may not correlate with radiographic progression.^{13,15,20,30,48,51,52} Patients often report symptomatic improvement despite ongoing structural degeneration, highlighting the complex interplay between mechanical restoration, neuromuscular adaptation, and patient perception.¹⁴ The study was not specifically powered to detect between-group differences in patient-reported outcome measures such as IKDC scores, which may explain the absence of statistical significance despite numerically greater improvement in the acute cohort.

MRI-based diagnostic findings—including the ghost sign and truncation sign—did not differ significantly between acute and chronic presentations. Although these signs are useful for identifying root pathology, they do not characterize the chronicity or biological severity of the tear.^3,5,12,43,49 Similarly, mechanical axis alignment was comparable between groups, suggesting that varus alignment—an established risk factor for medial compartment OA—did not confound group comparisons.^52-54

Taken together, these findings support a nuanced interpretation of surgical timing in medial meniscus root tears. Timing alone does not independently determine radiographic outcomes; instead, the degenerative state of the meniscus and cartilage at the time of surgery—largely a function of prolonged biological deterioration—plays the dominant role. Early diagnosis and timely referral thus remain crucial, not because delay directly worsens prognosis, but because delayed presentation is associated with more advanced degenerative changes at the time of surgery.

Limitations and Strengths

This study has several important strengths. First, OA progression was evaluated using objective, standardized radiographic parameters, including the KL grading system, which provides a comprehensive assessment of structural changes beyond joint space narrowing alone. The minimum 2-year follow-up period allowed for reliable evaluation of early radiographic progression following repair. The inclusion of patients from multiple institutions, all treated using an identical arthroscopic transtibial pullout technique, enhances external validity while maintaining procedural consistency. Additionally, the use of a priori power analysis strengthens the methodological rigor of the study, ensuring an adequate sample size to detect clinically meaningful differences.

Several limitations should also be acknowledged. As a retrospective cohort study, the design is subject to inherent risks of selection bias and incomplete data capture. Although 178 patients were initially reviewed, only 61 had complete imaging data suitable for analysis, which may limit the generalizability of the findings and introduce selection bias in the study group. Baseline differences between acute and chronic cohorts—particularly regarding meniscal extrusion and JSW—reflect the degenerative nature of chronic presentations but also introduce potential confounding that required statistical adjustment. All radiographic measurements were performed by a single primary evaluator, which may introduce observer-dependent bias; however, interobserver reliability was assessed in a small subsample (n = 8). While this limited sample size may reduce the precision of ICC estimates, preoperative KL grading demonstrated perfect agreement, and joint space measurements showed excellent reliability. Also, intraoperative chondral findings were not included as independent predictors of radiographic progression because these were not systematically graded or recorded in a standardized manner across institutions.

The lack of detailed classification of meniscal root tear morphology represents an additional limitation, as differences in tear pattern may influence healing potential and long-term structural outcomes. The multi-institutional design may have introduced variability in perioperative management and rehabilitation protocols; however, the standardized surgical technique across all sites mitigates concerns regarding technical inconsistency. Finally, the absence of second-look arthroscopy limited the ability to directly assess meniscal healing or cartilage status postoperatively, restricting conclusions to radiographic rather than arthroscopic or histologic endpoints.

Conclusion

This study found that patients treated in the chronic phase of medial meniscus posterior root tears demonstrated greater unadjusted radiographic progression of OA compared with those treated acutely. However, this difference was no longer significant after adjusting for baseline degenerative factors—including medial meniscus extrusion and preoperative JSW—indicating that worse outcomes in the chronic cohort were primarily associated with greater baseline degenerative burden present at the time of surgery rather than surgical delay alone. These findings suggest that while timing does not independently determine postoperative radiographic outcomes, delayed presentation is associated with more advanced degenerative changes—particularly greater meniscal extrusion—at the time of surgery. Early recognition and timely referral may therefore be associated with less advanced degenerative features at the time of surgery—particularly meniscal extrusion, joint space narrowing, and higher BMI—and a more favorable structural context in which medial meniscus root repair is performed.

Footnotes

Apppendix

Appendix Table 1

Multivariable Logistic Regression Predicting ≥1 Kellgren-Lawrence Grade Progression Over 2 Years

Predictor	Odds Ratio (95% CI)	P Value
Chronicity >3 months (vs ≤3 months)	8.46 (0.87-81.96)	.065
Age at surgery, y	1.08 (0.92-1.26)	.345
Male sex (vs female)	1.46 (0.09-24.67)	.792
Body mass index, kg/m²	1.21 (1.00-1.48)	.055
Preoperative Kellgren-Lawrence grade	0.01 (0.0004-0.34)	.010
Preoperative joint space width, mm	0.18 (0.03-0.98)	.048
Medial meniscal extrusion, %	1.09 (1.01-1.19)	.026
Mechanical axis, deg	1.10 (0.921.31)	.310

Final revision submitted January 7, 2026; accepted January 12, 2026.

The authors have declared that there are no conflicts of interest in the authorship and publication of this contribution. AOSSM checks author disclosures against the Open Payments Database (OPD). AOSSM has not conducted an independent investigation on the OPD and disclaims any liability or responsibility relating thereto.

Ethical approval for this study was waived by the Institutional Review Board of Rush University Medical Center (ORA #23083005-IRB01).

ORCID iDs

Ali Can Koluman

Udit Dave

Trevor Poulson

Lika Dzidzishvili

Adam B. Yanke

Jorge Chahla

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