Arthroscopic all-in technique combined with high tibial osteotomy for osteoarthritis with posterior root tear of the medial meniscus: a short-term study with second-look arthroscopy

Abstract

Background

Medial Meniscus Posterior Root Tears (MMPRTs) are known to accelerate medial compartment knee osteoarthritis (OA). This study aimed to evaluate the short-term clinical outcomes of arthroscopic all-suture anchor (ASA) repair combined with high tibial osteotomy (HTO) for patients with medial compartment OA and MMPRTs, offering a potential new surgical approach for this condition.

Methods

This study retrospectively reviewed 36 patients undergoing arthroscopic ASA repair combined with HTO for medial compartment OA with MMPRTs at our institution between June 2022 and June 2023. All patients underwent second-look arthroscopy during hardware removal. We collected demographic data (age, sex, affected side, duration of symptoms, complications), preoperative and postoperative Tegner activity scores, Lysholm scores, International Knee Documentation Committee (IKDC) scores, and Knee injury and Osteoarthritis Outcome Scores (KOOS). Radiographic comparisons (pre- and post-op) included Kellgren–Lawrence (K–L) grading, hip-knee-ankle angle (HKA), medial proximal tibial angle (MPTA), joint line convergence angle (JLCA), and posterior tibial slope (PTS). Medial meniscus extrusion rate (MMER) was also assessed. At second-look arthroscopy, the healing status of the medial meniscus posterior root was evaluated. Patients were subgrouped based on root healing status to examine correlations with clinical scores, MMER, K–L grade, and symptom duration.

Results

The cohort comprised 30 females (83.3%) and 6 males (16.7%), with a mean age of 59 years. Mean follow-up was 24.8 ± 2.4 months. Significant improvements were observed in all final scores: Lysholm (46.58 ± 16.04 to 79.08 ± 14.29), IKDC (37.08 ± 14.57 to 65.81 ± 12.33), KOOS total scores (116.50 ± 26.13 to 65.89 ± 15.50), and Tegner (1.00 ± 1.27 to 2.33 ± 1.15) (all P < 0.001). Subgroup analysis revealed no significant differences between healed and non-healed groups regarding Lysholm, IKDC, KOOS, Tegner scores, symptom duration, or K–L grade. No complications (infection, nonunion, neurovascular issues) occurred by final follow-up.

Conclusion

ASA repair combined with HTO provides significant short-term improvement in clinical outcomes for MMPRTs with medial compartment OA. However, meniscal root healing did not correlate with clinical improvement, suggesting mechanical realignment plays a primary role.

Introduction

Medial Meniscus Posterior Root Tears (MMPRTs) have gained significant clinical attention in recent years due to their unique location. Defined as radial tears within 1 cm of the bony attachment or avulsion injuries at the tibial insertion, MMPRTs account for approximately 10%-21% of all meniscal surgeries [1, 2]. Biomechanically, MMPRTs disrupt hoop tension, leading to pathological medial meniscus extrusion, increased medial compartment contact pressure (comparable to total meniscectomy), and ultimately accelerated osteoarthritis (OA) progression [3]. Evidence suggests MMPRTs repair yields better clinical outcomes than partial meniscectomy, with one long-term (10-year) follow-up reporting lower rates of subsequent total knee arthroplasty (TKA) after repair versus resection [4]. Therefore, repairing MMPRTs is critical for restoring hoop tension, distributing stress, and preventing OA progression [5].

Varus limb alignment is a significant risk factor for both MMPRTs and meniscal extrusion, with varus > 5° considered a poor prognostic factor for repair success [6]. High tibial osteotomy (HTO) for medial compartment OA with varus alignment has been shown to slow OA progression [7]. Consequently, combining HTO with MMPRTs repair represents a logical treatment strategy, with prior studies reporting good outcomes using pullout repair techniques alongside HTO [8, 9].

However, traditional pullout techniques can be complicated by suture interference with HTO plates/screws, the “bungee effect,” suture wear, and creep [9, 10]. To address these issues, we propose the innovative use of all-suture anchor (ASA) for MMPRTs repair in conjunction with HTO. Recent biomechanical studies support the effectiveness of ASA for medial meniscus posterior root repair [11], although ASA is used for meniscal repairs, no previous clinical studies explicitly combine ASA with HTO.

This study aims to assess the clinical scores, radiological outcomes, and second-look arthroscopic findings following arthroscopic ASA repair combined with HTO for MMPRTs with medial compartment OA. We hypothesised that ASA combined HTO would yield improved clinical and radiographic outcomes compared with baseline.

Materials and methods

Clinical data

Study population

This retrospective study analyzed 36 patients with medial compartment osteoarthritis (OA) and medial meniscus posterior root tears (MMPRTs) who underwent arthroscopic ASA suturing of MMPRTs combined with high tibial osteotomy (HTO) at our hospital between June 2022 and June 2023. After screening the surgical database, 43 consecutive patients were identified as eligible for inclusion based on the criteria. Among them, 7 patients (16.3%) were lost to follow-up due to being unreachable by telephone or failure to return for scheduled hardware removal and second-look arthroscopy. The remaining 36 patients (83.7%) constituted the final study cohort. To assess potential selection bias, we compared the baseline demographic characteristics (age, sex) of the 7 lost-to-follow-up patients with those of the 36 included patients and found no significant differences (all P > 0.05), suggesting that the final cohort was representative of the initial eligible population. Due to the retrospective and non-comparative nature of this study, its inferences are limited.

Senior surgeons performed all procedures. Ethical approval was obtained (IRB No. 2024-092-1).

Inclusion criteria

• Laprade type 2 MMPRTs confirmed on Magnetic Resonance Imaging(MRI)(ghost sign, truncation sign).

• Medial compartment OA, K-L grade II-III.

• Medial proximal tibial angle (MPTA) < 85°.

• Age 40–65 years.

• Medial tibiofemoral cartilage Outerbridge grade ≤ 3.

• Laprade classfication:

• Type I is an isolated, stable partial tear at the root of the meniscus.

• Type 2 is a complete radial tear at the root of the meniscus.

• Type 3 is a tear with a concomitant longitudinal/circumferential tear (commonly referred to as a “bucket handle” tear).

• Type 4 involves an oblique meniscus tear extending to the meniscus root, resulting in complete root avulsion.

• Type 5 describes a complete avulsion fracture at the base of the tibial plateau attachment site.

Exclusion criteria

• Requirement for concurrent ligament reconstruction or other major soft tissue procedures.

• Previous knee surgery on the affected side.

• Failed primary MMPRTs repair.

• Incomplete medical records or loss to follow-up.

General data

Collected data included sex, age, BMI, affected side, and postoperative complications.

Surgical technique

Patients were positioned supine. Following standard sterilization and draping, standard anteromedial (AM) and anterolateral (AL) arthroscopic portals were established. The knee was examined under gentle valgus stress, maintained between 0–30° flexion. Intra-articular structures (menisci, ACL, PCL, cartilage) were assessed. The medial meniscus posterior root was visualized via the AL portal. If access to the medial compartment was tight, pie-crusting release of the posterior oblique fibers of the superficial medial collateral ligament (sMCL) was performed to confirm the MMPRTs. The root remnant and tibial footprint were debrided and freshened using a shaver and curette. A 2.4 mm guide pin was drilled through a tibial guide targeting the anatomical root footprint. An epidural needle loaded with No. 1 PDS suture was passed through the tibial tunnel into the joint, and a suture retriever pulled the PDS out through the AM portal. The knot of the ASA was disengaged from its base and threaded through the PDS loop. Under arthroscopic visualization, the PDS suture was used to pull the ASA knot into the bone tunnel until flush with the cortex (Fig. 1). Tensioning the ASA tails deployed the anchor beneath the cortex, and the PDS was removed. The torn root was then sutured approximately 5 mm medial to the tear margin using a combination of loop and simple stitches under appropriate tension. Stability was confirmed with a probe (Fig. 2).

Fig. 1.

Arthroscopic view from the anterolateral portal showing the all-suture anchor (ASA) being pulled into the tibial tunnel (black arrow) at the anatomical footprint of the medial meniscus posterior root. The view is oriented with the medial femoral condyle (MFC) on the left and the tibial plateau (TP) below

Fig. 2.

Intra-operative arthroscopic view after repair, demonstrating a stable and well-tensioned suture (white arrow) at the repaired medial meniscus posterior root. The image is obtained via the anterolateral portal

Following arthroscopy, a 7-cm longitudinal incision was made over the proximal medial tibia. After releasing the superior border of the pes anserinus and distal sMCL fibers, Hohmann retractors were placed to protect posterior neurovascular structures. A Kirschner wire was drilled 35 mm distal to the medial joint line, directed towards the fibular head, ending 5 mm short of the lateral cortex. Fluoroscopy confirmed correct position before performing the osteotomy along the wire, carefully avoiding posterior structures. A second biplanar osteotomy cut was made ≥ 10 mm proximal to the first cut, starting at the patellar tendon insertion and angled at 110°. The osteotomy gap was opened according to the preoperatively calculated correction angle and intraoperative cartilage status (Outerbridge grade): the mechanical axis was aimed at 50–55% of the medial tibial plateau width for Outerbridge grade 1–2 cartilage damage, and at Fujisawa’s point for Outerbridge grade 3 damage. An osteotomy plate was fixed medially. The joint was irrigated, a drain placed, and the wound closed in layers.

Postoperative rehabilitation

Quadriceps isometrics and straight leg raises began immediately postoperatively. Touch-down weight-bearing with crutches was permitted. Knee flexion was limited to < 90° for the first 4 weeks. Partial weight-bearing commenced at 4–6 weeks, progressing to full weight-bearing by 6 weeks. Deep squatting was avoided for 3 months.

Outcome assessment

To assess the reliability of these imaging measurements, two independent orthopedic surgeons who were not involved in the surgical procedures and were blinded to all clinical outcomes, patient identities, and the other rater’s assessments, performed all measurements. The images (radiographs and MRIs) were presented in a random order. Each rater performed the measurements twice, with a two-week interval between sessions to minimize recall bias.

Clinical assessment utilized the Tegner activity score, Lysholm score and IKDC score preoperatively and at final follow-up.Additionally, the Knee Outcome and Osteoarthritis Score (KOOS) was used for comprehensive assessment at the final follow-up. This scale comprises 42 items, each scored on a 5-point Likert scale (4, 3, 2, 1, 0), yielding a maximum raw total score of 168. The scale includes five subscales: pain, symptoms, activities of daily living, recreation and sports function, and quality of life.Each subscale is calculated independently using the following formula: Converted Score = 100 − (Actual Raw Score × 100 / Possible Raw Score Range).Higher scores indicate better knee function and quality of life.Standing full-length weight-bearing radiographs obtained preoperatively and at hardware removal were used to assess K-L grade, HKA, MPTA, JLCA, and PTS. Preoperative and post-hardware removal MRI (1.5-T Achieva, Philips) assessed MMER. MMER (%) was calculated as: (Extruded meniscus width / Total meniscus width) x 100. Measurements were taken on three consecutive slices at the MCL level and averaged (Fig. 3). All patients underwent second-look arthroscopy during hardware removal. Root healing status was categorized as:

Fig. 3.

Schematic representation (a) and corresponding coronal MRI slice (b) illustrating the method for calculating the medial meniscus extrusion rate (MMER). MMER = (b / a) × 100%, where ‘a’ is the total width of the medial meniscus body, and ‘b’ is the width of the extruded portion beyond the medial tibial plateau margin (dotted line). The scale is inherent to the clinical MRI (slice thickness: 3 mm)

• Complete Healing: No tear, good synovial coverage, stable on probing.

• Partial Healing: Continuity present but reduced tension on probing.

• Non-healed: No continuity, no tension, no evidence of healing.

Statistical analysis

Statistical analyses were performed using SPSS version 24.0 (IBM Corp., Armonk, NY, USA). Continuous data are presented as mean ± standard deviation (SD) or median (interquartile range) as appropriate. The normality of data distribution was assessed using the Shapiro-Wilk test. For comparing preoperative and postoperative measurements of continuous variables, paired t-tests were used for normally distributed data, and the Wilcoxon signed-rank test was used for non-normally distributed data. The mean or median differences with their 95% confidence intervals (CIs) were calculated.

The Kellgren–Lawrence (K–L) grade, as an ordinal variable, is presented as median (interquartile range) and compared between preoperative and postoperative assessments using the Wilcoxon signed-rank test.

Categorical data are presented as frequencies and percentages. For subgroup analysis, patients with complete and partial healing were combined into a “Healed” group and compared to the “Non-healed” group. Between-group comparisons were performed using independent t-tests or Mann-Whitney U tests for continuous variables (based on normality), and the Chi-square or Fisher’s exact test for categorical variables, as appropriate.

Due to the retrospective nature of this study, a priori sample size calculation was not performed. The sample size was determined by the number of eligible patients who underwent the combined procedure within the specified study period. To assess the statistical power of our primary clinical outcome, a post-hoc power analysis was conducted for the change in the Lysholm score (primary functional outcome) using G*Power 3.1.9.7 (Heinrich-Heine-Universität Düsseldorf, Germany). With a sample size of 36, an effect size (Cohen’s d) of 1.87 (calculated from the observed mean difference of 32.5 points and pooled standard deviation of 17.34), and a two-sided alpha level of 0.05, the achieved statistical power was > 0.99. This indicates that the study had sufficient power (> 0.80) to detect a clinically meaningful improvement in knee function.

The interobserver and intraobserver reliabilities for measurements were verified by the intraclass correlation coefficient (ICC). ICC values between 0.8 and 0.9 were considered good.

Results

The study finally enrolled 36 patients: 30 females (83.3%) and 6 males (16.7%), mean age 58.92 ± 5.12 years. There were 21 right knees and 15 left knees. Mean follow-up duration was 24.8 ± 2.4 months. No complications (infection, nonunion, neurovascular issues) occurred by final follow-up. Patient demographic data are presented in Table 1.

Table 1.

Patient demographics and posterior root healing status

	Age	Sex	Pain Duration (mo)	Side	FU (mo)	Healing Status
1	65	F	120	R	12	Complete Healing
2	65	F	1	R	12	Partial Healing
3	53	M	6	L	12	Non-healed
4	65	F	48	L	12	Non-healed
5	58	F	120	R	12	Partial Healing
6	52	F	3	L	12	Partial Healing
7	54	M	3	L	12	Complete Healing
8	54	M	12	R	12	Non-healed
9	65	F	6	R	12	Non-healed
10	52	F	24	R	12	Partial Healing
11	65	F	36	L	9	Non-healed
12	54	F	4	R	17	Partial Healing
13	65	F	36	R	18	Non-healed
14	61	F	3	R	11	Complete Healing
15	59	F	2	L	11	Non-healed
16	57	F	1	R	12	Partial Healing
17	56	F	10	R	12	Non-healed
18	62	F	4	L	15	Partial Healing
19	59	F	1	L	13	Complete Healing
20	49	F	12	R	12	Complete Healing
21	57	M	12	R	13	Non-healed
22	57	F	36	L	12	Complete Healing
23	65	F	6	L	17	Non-healed
24	65	F	5	L	14	Non-healed
25	58	F	36	L	15	Non-healed
26	64	F	4	R	14	Complete Healing
27	49	F	6	R	17	Non-healed
28	64	F	1	L	12	Non-healed
29	51	F	1	R	12	Non-healed
30	57	F	2	R	12	Complete Healing
31	62	F	24	R	15	Non-healed
32	63	F	1	R	14	Complete Healing
33	65	F	36	L	12	Complete Healing
34	58	M	6	R	15	Non-healed
35	57	F	12	R	14	Partial Healing
36	59	M	3	L	14	Non-healed

Significant improvements were observed in all clinical scores at final follow-up: Lysholm scores improved from 46.58 ± 16.04 to 79.08 ± 14.29, IKDC scores from 37.08 ± 14.57 to 65.81 ± 12.33, KOOS total scores decreased (indicating improvement) from 116.50 ± 26.13 to 65.89 ± 15.50(all KOOS subscales showed significantly higher scores at the last follow-up)and Tegner activity scores from 1.00 ± 1.27 to 2.33 ± 1.15 (all P < 0.001) (Tables 2 and 3). Subgroup analysis showed no significant differences in postoperative Lysholm, IKDC, KOOS, or Tegner scores, or in K-L grade, between the healed group and the non-healed group (Table 4).

Table 2.

Comparison of preoperative and final follow-up clinical scores and imaging

	Preop	Final FU	t-value	P-value	95%CI
Tegner	1.00 ± 1.27	2.33 ± 1.15	– 7.135	<0.001	[0.93, 1.73]
IKDC	37.08 ± 14.57	65.81 ± 12.33	– 10.589	<0.001	[23.41, 34.03]
KOOS(total scores)	116.50 ± 26.13	65.89 ± 15.50	12.009	<0.001	[– 59.52, – 41.70]
Lysholm	46.58 ± 16.04	79.08 ± 14.29	– 11.190	<0.001	[26.63, 38.37]
MMER(%)	31.61 ± 11.74	32.53 ± 10.33	– 0.681	0.500	[– 4.72, 6.56]
HKA(°)	173.02 ± 2.43	179.96 ± 2.27	– 19.09	<0.001	[4.73, 6.19]
MPTA(°)	84.96 ± 2.20	90.06 ± 1.92	– 15.63	<0.001	[4.35, 5.83]
JLCA(°)	1.96 ± 1.19	1.93 ± 1.21	0.203	0.840	[– 0.44,0.38]
PTS(°)	9.76 ± 3.24	11.65 ± 3.85	– 3.355	0.002	[0.67, 3.09]
K–L grade	2 [1, 2]	2 [1, 2]	Wilcoxon signed-rank	0.661	–

Tegner: Tegner activity score; IKDC: International Knee Documentation Committee score; KOOS: Knee injury and osteoarthristyis outcome score; Lysholm: Lysholm score; MMER: Medial Meniscus Extrusion Rate

Table 3.

Comparison of KOOS subscale scores between preoperative and final Follow-up

KOOS	Preop	Final FU	P-value	95%CI
Pain	52.24 ± 29.60	92.82 ± 6.03	< 0.001	[30.83, 50.33]
Symptoms	47.22 ± 28.62	85.32 ± 10.85	< 0.001	[28.48, 47.73]
Activities of daily living	26.74 ± 16.31	46.57 ± 16.41	< 0.001	[14.24, 25.41]
Sport and recreation function	7.78 ± 10.00	17.78 ± 6.67	< 0.001	[6.34, 13.66]
Knee—related quality of life	12.50 ± 10.71	65.10 ± 17.09	< 0.001	[46.81, 58.39]

Table 4.

Subgroup analysis of root healing status after second-look (Complete healing n = 10, partial healing n = 8)

	Tegener	KOOS	IKDC	Lysholm	MMER(%)	K-L Grade (Median [IQR])	Pain duration(mo)
Healed Group (n = 18)	2.39 ± 1.04	68.67 ± 16.55	62.50 ± 11.53	77.89 ± 15.39	32.82 ± 8.49	2 [1, 2]	21.50 ± 37.59
Non-healed Group (n = 18)	2.28 ± 1.27	63.11 ± 14.31	69.11 ± 12.53	80.28 ± 13.44	32.23 ± 12.14	2 [1, 2]	14.22 ± 14.82
P	0.776	0.289	0.109	0.623	0.868	0.50	0.450

Significant coronal plane correction was achieved, with the HKA improving from a preoperative mean of 173.02 ± 2.43° to 179.96 ± 2.27° at final follow-up. The mean posterior tibial slope (PTS) increased significantly from 9.76 ± 3.24° preoperatively to 11.65 ± 3.85° at final follow-up (P < 0.05). There was no significant change between preoperative and postoperative K–L grades (P > 0.05).

On final follow-up MRI, the medial meniscus extrusion rate (MMER) increased in 17 patients (47%) and decreased in 19 patients (53%). The mean MMER increased slightly from 31.61 ± 11.74% to 32.53 ± 10.33%, but this change was not statistically significant (P = 0.5).

Second-look arthroscopy findings: 10 patients (28%) demonstrated complete healing (Fig. 4), 8 (22%) partial healing, and 18 (50%) Non-healed (Figs. 5, 6). All patients showed clinical improvement. Subgroup analysis comparing the Healed group (Complete + Partial) to the Non-healed group revealed no significant differences in postoperative Tegner, IKDC, KOOS, Lysholm scores, MMER, symptom duration, or K–L grade (P > 0.05 for all, Table 4).

Fig. 4.

Second-look arthroscopic findings of the medial meniscus posterior root healing status (views from the anterolateral portal). Complete healing: The root is continuous, covered by synovium, and stable to probing

Fig. 5.

Artial healing: Continuity is preserved but the tissue appears attenuated with reduced tension

Fig. 6.

Non-healed: The root remains detached with no evidence of bridging tissue

With respect to the intra- and interobserver reliability, excellent agreement was observed for both reliability measures for pre- and postoperative measurements (ICC values ranging from 0.83 to 0.89) .(Tables 5 and 6).

Table 5.

Intra observer ICC

	Pre-op	Post-op
MMER	0.83	0.86
HKA	0.89	0.88
MPTA	0.84	0.86
PTS	0.87	0.89

Table 6.

Inter observer ICC

	Pre-op	Post-op
MMER	0.88	0.84
HKA	0.86	0.88
MPTA	0.88	0.84
PTS	0.83	0.84

Discussion

The key finding of this study was that arthroscopic ASA repair combined with HTO significantly improved short-term clinical outcomes in patients with MMPRTs and medial compartment OA at a mean follow-up of 24.8 months. Second-look arthroscopy revealed complete healing in 28% and partial healing in 22% of roots. The healing status did not significantly correlate with short-term outcomes; long-term implications remain unclear.

Significant enhancements in Lysholm, IKDC, KOOS, and Tegner scores demonstrate the efficacy of this combined technique, achieving outcomes comparable to those reported for pullout repair combined with HTO [12]. This is the first clinical report on ASA combined with HTO. ASA repair offers potential advantages over pullout techniques, including avoiding suture-plate/screw interference, the “bungee effect,” suture wear, and creep [9, 10], and potentially reducing risk to posterior neurovascular structures compared to suture anchor. The tibial tunnel placement also avoids conflict with the HTO site. By reducing medial compartment pressure, HTO may create a more favorable environment for root healing. Biomechanically, ASA have shown superiority to pullout techniques in restoring contact area under load, achieving near-normal tibiofemoral contact mechanics [13].The relatively short follow-up period of our study may account for this discrepancy.

While MMPRTs repair aims to restore function and prevent OA progression, medial meniscus extrusion (MME) remains a key risk factor for OA advancement. Studies on MME correction post-repair show conflicting results [14, 15]. Our study found no significant overall change in MMER, suggesting root repair alone may not consistently resolve extrusion; factors like surgical technique, rehabilitation protocol, and healing status likely influence MME. Chung et al.¹⁶ reported K-L progression in 68% of patients after pullout repair at short-term follow-up. In contrast, only 8% (3/36) of our cohort showed K-L progression at 2 years, with 86% stable and 6% improved. This suggests the combination of HTO with repair may better delay OA progression, although significant reversal is unlikely.

Our second-look healing rates (28% complete, 22% partial, 50% Non-healed) are lower than the 48% complete, 42% partial, and 10% Non-healed reported in a systematic review [17]. We frequently observed suture cut-through as a primary Non-healed cause, potentially due to excessive tension during fixation or premature loading during rehabilitation. Biomechanical studies suggest optimal initial suture tension is around 30N [18], and weight-bearing or motion exceeding the repair’s tolerance can generate damaging forces [19]. The learning curve associated with this technique might also have contributed to suboptimal tunnel placement in some cases. Accurate anatomical tunnel positioning (posterolateral direction) is critical for reducing extrusion and improving healing rates [20, 21].

Most significantly, subgroup analysis revealed no difference in clinical outcomes between patients with healed versus non-healed roots. This implies that for patients with MMPRTs and varus malalignment, HTO alone may yield good clinical results even if the root fails to heal. The mechanical correction provided by HTO, altering medial compartment pressure and the local microenvironment, appears to be the pivotal factor driving clinical improvement. This finding aligns with several studies reporting comparable outcomes between HTO alone and HTO combined with MMPRTs repair [22–25]. Kim et al. [22] reported that the presence of a posterior root tear in the medial meniscus did not affect the clinical efficacy of medial open wedge osteotomy at mid-term follow-up, suggesting that alignment correction is of primary importance. More instructive are studies with secondary observational evidence: Nha et al. [24] found that a high proportion of posterior root tears underwent complete or partial healing after HTO alone, yet this spontaneous healing was unrelated to clinical improvement—echoing our core observation. The most compelling evidence comes from direct comparative studies. Both Ke et al. [26] and Lee et al. [28] concluded through matched analyses that adding arthroscopic meniscal repair during HTO provides no significant clinical benefit for patients with posterior root tears. Lee et al. [28] specifically summarized that there is currently no clear evidence supporting the necessity of concurrent repair of posterior root tears during HTO. Therefore, the combined evidence, including our short-term results using the ASA repair technique, further supports the hypothesis that mechanical realignment and weight-bearing redistribution achieved through HTO are the key drivers of clinical success in patients with varus deformity and medial compartment osteoarthritis. The necessity of routinely supplementing this procedure with root repair in this specific context warrants further critical evaluation.

The significant postoperative increase in PTS warrants attention. This likely stems from greater anterior gap opening during medial opening-wedge HTO. Contributing factors include easier surgical access anteriorly, plate placement location (more anterior placement increases PTS) [30], and greater resistance from posterior soft tissues (sMCL origin) [29]. Increased PTS is a known risk factor for ACL/PCL injury [31, 32]. Mitigation strategies include placing distractors posteriorly to create a slightly trapezoidal gap and ensuring adequate release of the pes anserinus/sMCL [33].

Limitations

This study has limitations inherent to its retrospective design, including potential selection bias. The sample size is relatively small, and the follow-up period is short-term; larger, long-term studies are needed. Due to the absence of a control group (e.g., patients undergoing tibial osteotomy alone or alternative repair techniques), while our findings align with existing comparative literature, it remains challenging to definitively attribute clinical improvements solely to combined ASA-HTO surgery.The learning curve associated with the ASA technique may have affected tunnel placement accuracy and suture tension control, potentially influencing healing rates.

This study involved multiple comparisons across several outcome measures. No statistical adjustment for multiple testing was performed, which increases the risk of Type I error (false positive). However, the robustness of our primary conclusions is supported by the following: (1) the improvements in all primary patient-reported outcome measures (Lysholm, IKDC, KOOS, Tegner) and key radiographic alignment parameters (HKA, MPTA) were highly significant (all P < 0.001); (2) even under the most conservative Bonferroni correction for the 9 primary comparisons in Table 2 (adjusted α = 0.05/9 ≈ 0.0056), these improvements remain statistically significant. Therefore, while the lack of correction is a limitation, it does not invalidate the main finding that the combined procedure significantly improves knee function and alignment in the short term.

Moreover, postoperative MRI assessments primarily focused on quantifying meniscal migration (MMER) without systematically evaluating other potentially relevant features such as cartilage condition, bone marrow lesions, or detailed morphological characteristics of the healing root. These factors could have provided deeper insights into the joint’s postoperative structural response.

Conclusion

ASA repair combined with HTO provides significant short-term improvement in clinical outcomes for MMPRTs with medial compartment OA. However, meniscal root healing did not correlate with clinical improvement, suggesting mechanical realignment plays a primary role.

Author contributions

J.T.D. carried out and designed the study. X.D.Z., Y.Z., Y.Z.N. analyzed the data. All authors contributed to data collection. Y.Z. and X.D.Z. wrote the manuscript., and J.T.D. approved the final version of the manuscript. All of the authors read and approved the final manuscript. Xinda Zhang is the first author and Yi Zheng is the co-first author.

Funding

None.

Data availability

All data generated or analysed during this study are included in this published article.

Declarations

Consent for publication

Not applicable.

Competing interests

The authors declare no competing interests.

Ethical approval and consent to participate

This study conforms to the provisions of the Declaration of Helsinki and has been reviewed and approved by the Institutional Review Board (IRB) of the Third Hospital of Hebei Medical University (IRB number: KE 2024-092-1).The patient had given the informed consent to allow their information to be used in research purposes and informed consent was obtained from the participant. Clinical trial number: not applicable.