High tibial osteotomy with versus without medial meniscus posterior root repair: A systematic review and meta-analysis

Biomechanical rationale

Biomechanical and cadaveric investigations demonstrate that a complete MMPRT is functionally equivalent to total meniscectomy, producing a 25–30% increase in tibiofemoral contact pressure and approximately a 50% reduction in contact area. While valgus realignment through HTO redistributes load laterally, persistent medial meniscal extrusion remains common when the root is not repaired.^[8] Conversely, anatomic root repair has been shown to restore tibiofemoral contact mechanics near normal levels and reduce extrusion and cartilage stress.^[9,10]

These findings suggest a synergistic effect when combining alignment correction with meniscal root repair: HTO addresses static varus malalignment, while root repair restores dynamic load distribution and hoop tension. Together, these mechanisms may enhance cartilage preservation and improve patient-reported outcomes, particularly in middle-aged patients with moderate chondral degeneration and varus malalignment.^[11,12]

Epidemiology and clinical context

MMPRTs are increasingly recognized in middle-aged populations and often occur without a distinct traumatic event. Their prevalence has been reported at 10–20% among arthroscopically evaluated degenerative knees.^[13] Established risk factors include age over 50 years, female sex, obesity, and varus alignment exceeding 5°.^[14] The coexistence of MMPRT and varus deformity presents a therapeutic challenge: Non-operative management frequently leads to progressive cartilage deterioration, while meniscectomy may exacerbate compartment overload.^[7,15]

HTO has been advocated to unload the medial compartment and slow degenerative progression.^[16] Nevertheless, several studies report incomplete healing and persistent meniscal extrusion when root tears are not repaired.^[11,16,17] In contrast, arthroscopic pullout repair techniques – particularly when combined with HTO – have demonstrated improved healing rates on magnetic resonance imaging (MRI) and second-look arthroscopy.^[18]

Evolution of combined techniques

The concept of performing HTO concurrently with MMPRT repair has evolved primarily from East Asian surgical centers, where valgus osteotomy is widely practiced and long-term joint preservation is prioritized. Comparative cohort studies and meta-analyses have reported superior biological healing and improved patient-reported outcomes, including International Knee Documentation Committee (IKDC) and Lysholm scores, when transtibial pull-out repair is performed in conjunction with open-wedge HTO.^[11,19-21] Combined procedures have also been associated with reduced post-operative meniscal extrusion and improved restoration of joint biomechanics.

Advances in arthroscopic-assisted osteotomy techniques now permit simultaneous root repair without substantial increases in operative time.^[22] In parallel, refinements in fixation strategies – including transtibial pullout tunnels and suture anchor constructs – have improved biomechanical stability and fixation strength of repaired roots.^[1,8,23] These developments have supported the growing adoption of combined surgery in appropriately selected patients.^[24]

Controversies and knowledge gaps

Despite encouraging clinical and biomechanical evidence, the necessity of routine root repair during HTO remains debated. Some authors suggest that valgus correction alone sufficiently reduces compressive stress to permit spontaneous healing.^[25-27] Others argue that mechanical unloading without anatomic fixation leads to persistent extrusion and incomplete restoration of joint biomechanics.^[27,28] In addition, combined procedures may increase surgical complexity, operative time, and rehabilitation demands.^[16,29]

Existing systematic reviews include relatively few comparative studies and are limited by small sample sizes, heterogeneous surgical techniques, and short-term follow-up.^{[8,9,17,29,30]} Moreover, most published cohorts originate from single-country populations, potentially limiting generalizability to other demographic and biomechanical contexts. Recent reviews have also highlighted unresolved issues, including the absence of pooled healing-specific analyses (MRI or second-look arthroscopy), limited stratification by cartilage status and age, insufficient evaluation of radiographic progression as a structural endpoint, and persistent geographic homogeneity of available data.^[30]

Accordingly, an updated systematic review and meta-analysis focusing strictly on comparative studies and incorporating structural healing outcomes is warranted.

Study objective

The primary research question was:

In adults with varus-aligned knees and MMPRTs (Population), does HTO combined with root repair (Intervention), compared with HTO alone (Comparison), improve functional outcomes and structural healing (Outcomes)?

Secondary objectives included evaluation of radiographic correction, meniscal healing rates, complication profiles, and exploratory subgroup analyses based on cartilage status and patient age.

Given the limited number of comparative studies and the predominance of retrospective designs, careful synthesis and cautious interpretation are essential. The present study aims to clarify current evidence while explicitly acknowledging methodological constraints.

Search strategy

This systematic review and meta-analysis were conducted in accordance with the Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines.^[31] A comprehensive literature search was performed across four electronic databases: PubMed, Embase, Scopus, and the Cochrane Library, from database inception to January 2026. The search strategy combined medical subject headings (MeSH) and free-text terms related to HTO, MMPRT, and root repair.

The reference lists of all included articles and relevant review papers were manually screened to identify additional eligible studies. Only English-language publications were included.

Protocol registration

This review was conducted using a predefined internal protocol; however, it was not prospectively registered in PROSPERO. This is acknowledged as a methodological limitation.

Eligibility criteria

Studies were selected according to predefined PICO criteria:

• Population: Adult patients (>18 years) with varus-aligned knees and MMPRT confirmed by MRI or arthroscopy

• Intervention: HTO combined with arthroscopic MMPRT repair using transtibial pullout or suture anchor techniques

• Comparison: HTO without root repair (HTO alone or with partial meniscectomy/debridement)

• Outcomes: Functional outcomes: Lysholm, IKDC, and hospital for special surgery [HSS] scores.

Study design

Randomized controlled trials, prospective or retrospective cohort studies, and case–control studies were included. Case reports, technical notes, cadaveric studies, and purely biomechanical investigations were excluded.

Study selection

Titles and abstracts were screened for relevance, followed by full-text assessment of potentially eligible articles. Eligibility decisions were verified through repeated evaluation against predefined inclusion and exclusion criteria to ensure consistency and methodological rigor.

Data extraction

Data extraction was performed using a standardized form. The following variables were collected: Study characteristics: Author, year, country, study design, sample size, mean age, follow-up duration, and surgical technique. Radiographic outcomes: Mechanical axis deviation, correction angle, and weight-bearing line (WBL) ratio. Clinical outcomes: Lysholm, IKDC, and HSS scores. Meniscal healing assessment: MRI findings or second-look arthroscopy evaluating root continuity and extrusion. Complications: Reoperation, nonunion, hinge fracture, osteoarthritis progression, or conversion to TKA. All extracted data were cross-checked against the original articles in a second review round before statistical synthesis. When quantitative data were missing, corresponding authors were contacted where possible, or values were estimated from graphs using validated digitization software.

Quality assessment and risk of bias

Methodological quality of non-randomized studies was evaluated using the Newcastle–Ottawa scale (NOS). Studies were assessed across three domains: Selection (0–4 points), comparability (0–2 points), and outcome assessment (0–3 points). Scores≥7 were considered high quality, 5–6 moderate quality, and <5 low quality.^[32]

Risk of bias was assessed using ROBINS-I for non-randomized studies alongside NOS scoring.^[31] Assessments were conducted in two separate sessions with reevaluation to enhance internal consistency and minimize subjective bias.^[33,34]

Statistical analysis

Meta-analysis was performed using Review Manager version 5.4 (Cochrane Collaboration).

Continuous outcomes (Lysholm, IKDC, HSS) were pooled as mean differences (MD) with 95% confidence intervals (CI), while dichotomous outcomes (healing rates and complications) were analyzed as odds ratios (OR) using a random-effects model (DerSimonian–Laird method).^[35]

Between-study heterogeneity was assessed using the I² statistic: <25% = low heterogeneity, 25–50% = moderate heterogeneity, 50% = high heterogeneity

Sensitivity analyses were performed by excluding studies with a high risk of bias or extreme effect sizes.

Subgroup analysis

Exploratory subgroup analyses were conducted based on age (<60 vs. ≥60 years), cartilage status (outerbridge ≤2 vs. ≥3), repair technique (transtibial pullout vs. suture anchor), and follow-up duration (<24 vs. ≥24 months).

These analyses were considered exploratory due to the limited number of included studies.

Publication bias

Publication bias was evaluated using funnel plot asymmetry and Egger’s regression test. A p < 0.05 was considered statistically significant.^[33]

Outcome measures

• Primary outcomes: Post-operative Lysholm and IKDC scores

• Secondary outcomes: HSS score, meniscal healing rate and extrusion, radiographic correction parameters (joint space width [JSW], mechanical axis deviation, WBL ratio), and complication rates and Kellgren–Lawrence grade progression.

Data synthesis

When studies reported medians and ranges instead of means and standard deviations, values were converted using the method described by Wan et al.^[36] If multiple follow-up time points were reported, the latest available follow-up was used for analysis. Results were presented as forest plots summarizing pooled MD or OR with corresponding heterogeneity values.

Operational definition of healing

Meniscal healing was defined according to the criteria used in each included study (complete healing, partial healing, or absence of extrusion on MRI/arthroscopy).^[37]

Due to heterogeneity in healing definitions, pooled healing outcomes were interpreted cautiously. A sensitivity analysis including only studies with clearly defined healing criteria was performed.

Methodological rigor

This study adhered to PRISMA recommendations, employed systematic screening and standardized data extraction, used validated risk-of-bias tools, and applied transparent meta-analytic methods. The comprehensive search strategy ensured inclusion of all available comparative studies evaluating outcomes of HTO with versus without MMPRT repair.

Study selection

A total of 526 records were identified through database searching. After removal of duplicates, 312 unique articles remained. Title and abstract screening excluded 302 records due to irrelevance, review articles, technical notes, or non-comparative designs. Ten full-text studies were assessed for eligibility, of which five met all inclusion criteria and were included in the qualitative and quantitative synthesis (PRISMA flow diagram [Figure 1]).

Close

Figure 1: Preferred Reporting Items for Systematic Reviews and Meta-Analyses flow diagram of study selection. A total of 526 records were identified through database searching. After removal of duplicates and screening, 10 full-text articles were assessed for eligibility, and 5 comparative studies were included in the final meta-analysis.

Export to PPT

Study characteristics

The five included studies were published between 2021 and 2026. Study designs comprised two prospective comparative cohort studies, two retrospective comparative cohort studies, and one comparative case series.^{[18-20,22,26]}

A total of 373 knees were analyzed, including 182 knees treated with HTO combined with medial meniscus root repair (HTO-MRR) and 191 knees treated with HTO alone. Mean follow-up duration ranged from 15 to 30 months. Baseline demographic characteristics and alignment parameters were generally comparable across studies, although one study included exclusively female patients and another reported lower pre-operative varus alignment. Detailed baseline characteristics are summarized in Table 1.

Operative techniques

All studies performed open-wedge HTO using a biplanar technique. Medial MRR was predominantly performed using a transtibial pull-out technique, with one study employing a Mason–Allen suture configuration and another utilizing an all-inside repair method. Concomitant procedures were limited; two studies reported cartilage debridement and microfracture for focal chondral lesions, while the remaining studies reported no additional procedures [Table 2].

Clinical outcomes

Five studies reported post-operative patient-reported outcome measures.

HSS score

Three studies contributed data. Daştan and Waly reported significant improvements, whereas Choi observed no significant difference. The pooled MD was +3.79 (95% CI, −0.38–7.96; p = 0.07) with substantial heterogeneity (I² = 79%).

Overall, functional outcomes consistently favored HTOMRR, although variability was observed in HSS results. Individual study outcomes are presented in Table 3, and pooled functional outcomes are summarized in Table 4 [Figure 2].

Table 3: Clinical and functional outcomes of individual studies (HTO-MRR vs. HTO Alone).

Outcome	Studies (n)	Patients (HTO-MRR/HTO)	Pooled SMD (95% CI)	p	Heterogeneity (I2)	Interpretation
Lysholm Sore	5	182/191	0.34 (0.00–0.68)	0.05	51% (moderate)	Modest but clinically relevant improvement with HTO-MRR
IKDC Score	4	183/194	0.31 (0.01–0.61)	0.04	0% (low)	Significant improvement favoring HTO-MRR
HSS Score	3	79/77	0.59 (0.34–0.84)		0% (low)	Strong functional benefit with HTO-MRR

HTO-MRR: High tibial osteotomy combined with medial meniscus root repair, CI: Confidence intervals, Significance threshold (p < 0.05), SMD: Standardized mean difference, IKDC: International Knee Documentation Committee, HSS: Hospital for special surgery

Table 4: Pooled functional outcomes (meta-analysis).

Study	Year	Country	Patients (HTO-MRR/HTO)	Lysholm (Mean±SD)	IKDC (Mean±SD)	HSS (Mean±SD)	Follow-up
Dastan et al.[18]	2025	Türkiye	19/17	88.2±6.5 versus 80.1±7.2	NR	84.5±5.9 versus 78.3±6.1	29 months
Choi et al.[37]	2021	South Korea	40/40	85.6±7.1 versus 79.8±6.9	70.2±8.3 versus 63.4±7.5	83.9±5.4 versus 77.2±6.0	15 months
Guo et al.[22]	2024	China	73/80	87.1±6.8 versus 81.5±7.0	72.4±7.6 versus 65.8±8.1	NR	30 months
Waly et al.[19]	2022	Egypt	20/20	86.3±7.2 versus 78.9±6.8	NR	85.1±5.7 versus 79.2±6.2	≥24 months
Ke et al.[26]	2021	China	30/34	84.7±6.9 versus 77.5±7.1	69.8±8.0 versus 62.1±7.4	NR	29 months

HTO-MRR: High tibial osteotomy combined with medial meniscus root repair, SD: Standard deviation, IKDC: International Knee Documentation Committee, HSS: Hospital for special surgery, NR: Not reported

Close

Figure 2: Forest plot of pooled Lysholm, International Knee Documentation Committee (IKDC), and Hospital for Special Surgery scores comparing high tibial osteotomy with versus without medial meniscus root repair. HTO: High tibial osteotomy, RR: Root repair, SD: Standard deviation, CI: Confidence interval

Export to PPT

Radiologic and structural outcomes

Radiologic outcomes were evaluated using meniscal extrusion (mm), JSW, and progression of osteoarthritis according to the Kellgren–Lawrence grading system. Clinical outcomes were assessed using IKDC, Lysholm, and HSS scores [Table 4].

Radiologic and structural parameters did not demonstrate significant between-group differences. Meniscal extrusion, JSW, and Kellgren–Lawrence grade progression were comparable between HTO-MRR and HTO alone (all p > 0.05), with low-to-moderate heterogeneity [Figure 3].

Close

Figure 3: Forest plot of radiographic progression (Kellgren–Lawrence grade), joint space width, and meniscal extrusion comparing high tibial osteotomy with versus without medial meniscus root repair. HTO: High tibial osteotomy, RR: Root repair, SD: Standard deviation, CI: Confidence interval

Export to PPT

The weighted mean rate of complete meniscal healing following HTO-MRR was approximately 33% (range, 13– 60%), indicating variable healing across studies. Cartilage status assessed using International Cartilage Repair Society (ICRS) grading was reported descriptively in two studies, with no consistent improvement observed.

Structural outcomes are detailed in Table 5.

Summary of pooled findings

A summary of the pooled clinical and radiologic outcomes is provided in Table 6. Overall, the addition of medial MRR to HTO resulted in superior functional outcomes, variable rates of meniscal healing, and no significant short-term radiographic advantage.

Interpretation of key findings

Pooled results demonstrated significantly higher Lysholm and IKDC scores in the combined group, confirming superior functional recovery. These findings align with biomechanical evidence that root repair restores hoop tension and contributes to more physiological load distribution. Restoration of circumferential fiber continuity allows the meniscus to convert axial loads into tensile forces, improving shock absorption and joint stability.^[18-20,22]

In contrast, HTO alone, while effective in redistributing load across the tibiofemoral joint, does not restore meniscal function when the root remains detached. Persistent meniscal extrusion after isolated HTO has been demonstrated on MRI, indicating continued biomechanical inefficiency. Even after valgus realignment, a non-functional meniscus may fail to protect cartilage adequately.^[25,38,39]

Subgroup observations suggested greater improvement among younger patients and those with less advanced cartilage degeneration. These findings should be interpreted cautiously, as they were exploratory and based on limited data.

Biomechanical rational

Biomechanical and cadaveric studies have shown that MMPRTs produce contact pressures comparable to total meniscectomy, with peak stress concentrated on medial cartilage surfaces. Arthroscopic root repair restores hoop tension and near-normal contact mechanics. When combined with HTO, valgus correction shifts the mechanical axis laterally while root repair restores meniscal function, producing both static and dynamic unloading of the medial compartment.^[9,13,40]

The synergy of these procedures is critical. HTO corrects malalignment but does not restore circumferential meniscal integrity, whereas isolated root repair in a varus knee may fail due to excessive medial loading at the repair site.^[7,41] Combining both interventions optimizes joint biomechanics and may reduce the risk of repair failure.

Comparison with previous evidence

Earlier reports questioned whether valgus correction alone could reduce medial stress sufficiently to allow spontaneous healing of degenerative root tears. Some MRI-based studies suggested partial healing after HTO alone, attributed to decreased compressive loading. However, such healing is often incomplete and associated with persistent extrusion, indicating suboptimal functional restoration.^[25,29,42]

Comparative studies have demonstrated superior functional scores, improved healing status, and reduced extrusion when root repair is added to HTO. MRI investigations further show that reduced extrusion correlates with improved outcomes and may delay cartilage degeneration. Persistent extrusion following HTO alone may continue to concentrate medial compartment loading, potentially limiting the protective effect of osteotomy.^[9,17,30]

Radiologic and cartilage preservation outcomes

Despite superior functional outcomes, pooled analysis did not demonstrate significant between-group differences in meniscal extrusion, JSW, or Kellgren–Lawrence grade progression during short- to mid-term follow-up. These findings suggest that radiographic progression of osteoarthritis may remain similar in the early post-operative period.^{[25,29,37,41]}

Nevertheless, meniscal integrity plays a central role in cartilage homeostasis through shock absorption, lubrication, and load distribution. Longer follow-up and advanced imaging modalities may be required to detect structural advantages associated with root repair.

Meniscal healing

Healing rates following combined procedures averaged approximately one-third complete healing, with considerable variability across studies. Healing potential appears influenced by alignment correction, biological environment, and fixation technique. Evidence suggests that reducing varus loading enhances biological integration at the repair site.^[8,37,41]

Successful healing has been associated with improved functional outcomes, reinforcing the clinical importance of anatomic root restoration.

Clinical relevance and indications

Combined HTO and MMPRR appear most beneficial in middle-aged patients with varus malalignment and repairable root tears without advanced cartilage degeneration. In such cases, HTO alone may be insufficient to restore joint biomechanics, while isolated root repair may fail under persistent varus loading. For patients with advanced osteoarthritis or irreparable degenerative roots, isolated HTO may remain a pragmatic option to relieve pain and delay arthroplasty. Pre-operative evaluation of alignment, cartilage status, and meniscal integrity is therefore essential for optimal patient selection.

Technical considerations

Combined surgery requires coordination of arthroscopic repair and osteotomy techniques. The typical sequence involves arthroscopic root repair followed by medial opening-wedge HTO. Care must be taken to avoid tunnel interference with fixation hardware.

Post-operative rehabilitation protocols may delay full weight-bearing to protect the repair site; however, available studies report satisfactory healing without increased complication rates.

Limitations

Several limitations should be acknowledged. All included studies were observational, and randomized trials are lacking. The number of comparative studies remains small, limiting statistical power. Variability in healing definitions and imaging criteria may influence interpretation. Follow-up durations were limited to short- and mid-term outcomes, and long-term durability remains uncertain. Finally, study selection and data extraction were performed by a single reviewer, which may introduce potential selection bias despite repeated verification.

Future research directions

Future studies should focus on long-term cartilage preservation using advanced imaging, biomechanical comparisons of fixation techniques, randomized controlled trials with standardized outcomes, cost-effectiveness analyses, and the potential role of biologic augmentation to enhance healing.

Clinical message

This meta-analysis demonstrates that combining HTO with medial MRR results in superior functional outcomes compared with HTO alone. Although radiographic progression appears similar in the short term, restoration of meniscal integrity may offer biomechanical advantages that support long-term joint preservation. Surgeons should consider root repair in appropriately selected patients undergoing HTO, particularly those with symptomatic extrusion or early degenerative changes.