Functional outcome of medial meniscal posterior root repair with medial opening wedge osteotomy with early osteoarthritis and meniscal root tear: A prospective observational study

INTRODUCTION

The menisci of the knee are fibrocartilaginous structures composed of type 1 collagen interlaced with proteoglycans, glycoproteins, and cellular elements. Their wedge-like cross-section deepens the tibial plateau and increases contact surface area between the tibial plateau and the femoral condyle, which allows uniform load transmission on axial loading.^[1,2] The circumferential fibers of a healthy meniscus transform vertically applied compressive forces on the knee into axially directed “hoop stresses,” promoting uniform load distribution to the chondral surfaces and safeguarding the articular cartilage.^[3] Tears at the meniscus root and radial tears within 10 mm of the root attachment have shown decreased joint contact areas and increased contact pressures on flexion.^[3,4] Therefore, from a biomechanical standpoint, a medial meniscus posterior root tear (MMPRT) resembles a complete meniscectomy^[3] accelerating articular cartilage damage.

Tears of the medial meniscal posterior root are primarily degenerative, often occurring without injury.^[5] Factors contributing to the MMPRT include varus malalignment, advancing age, elevated body mass index (BMI), and being female.^[6] Diagnosing these cases requires a heightened awareness due to the lack of a noticeable injury. Patients typically report pain along the joint line, with popping sounds when standing up from a chair or squatting, and rarely mechanical symptoms like locking or catching.^[7] The most frequently observed findings during a physical examination include tenderness at the joint line, pain during complete knee flexion, and a positive McMurray test.^[8]

The treatment for MMPRT has evolved over time, with initial management protocols being limited to conservative management including lifestyle modifications, bracing and hot fomentation, use of oral nonsteroidal anti-inflammatory drugs (NSAIDs), and intra-articular injections of platelet-rich plasma or corticosteroids. Non-responders were advised radical surgical procedures such as partial/total meniscectomy, which has since fallen out of favor, as long-term follow-up found that this procedure accelerates articular cartilage degeneration.^[9]

Current treatment methods aim to restore the anatomical and biomechanical integrity of the meniscus and to postpone the onset of osteoarthritis (OA). Multiple management options have been devised, but a lack of consensus in the treatment complicates the decision-making process. Good outcomes have been seen with arthroscopic medial meniscus posterior root repair (MMPRR), with conservative management being reserved only for elderly patients with high-grade OA - Kellgren–Lawrence (KL) grade 4, or patients with comorbidities.^[10] In cases with an additional component of varus malalignment of >4°, medial open wedge high tibial osteotomy (MOW-HTO) in conjunction with MMPRR has been suggested.^[11]

Although HTO alone can provide symptomatic relief in patients with MMPRT without the need for meniscal repair,^[12] they do not address the meniscal extrusion and loss of “hoop stress” in the joint. Hence, a combined approach (MMPRR with MOW- HTO) in middle-aged patients having early OA (KL grade 2,3) with varus malalignment shows better objective outcomes with respect to meniscus healing and cartilage stability scores, as is supported by literature.^[13]

This clinical conundrum is further complicated by the lack of long-term reports, especially with respect to the Indian population, where literature is scarce. In this paper, we present a series of patients with MMPRTs and early OA who underwent arthroscopic MMPRR with MOW-HTO. It follows the patients over a period of 12 months, outlines the preoperative evaluation, surgical technique, follow-up protocol, and highlights the functional outcome. This study also aims to close the gaps in our knowledge of this condition in an Indian context.

MATERIALS AND METHODS

This prospective observational study was carried out at a tertiary care center in Lucknow, Uttar Pradesh, between April 2023 and August 2024.

Preoperative evaluation

Every patient with knee pain first underwent conservative management for at least 2 months. Detailed history was taken to determine the duration and severity of symptoms, followed by a thorough physical examination to look for signs of medial meniscal root tear, such as pain on deep flexion, medial joint line tenderness, and a positive McMurray’s test. Visual Analog Scale (VAS) score for pain, Tegner Lysholm (TL) score, and International Knee Documentation Committee (IKDC) score were calculated to estimate the preoperative function of the knee. At this time, radiological examination with plain standing radiographs (anteroposterior, lateral, and skyline views) was also done to rule out advanced arthritis or bony deformities [Figure 1a], and the KL grade of OA was noted.

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Figure 1: 47-year-old woman with complaints of pain and swelling of the left knee diagnosed with medial compartment osteoarthritis (Kellgren Lawrence grade 2). (a) Plain radiograph of the left knee in anteroposterior and lateral views shows reduced medial joint line space (red arrow) with varus deformity at the left knee. (b) Magnetic resonance imaging of the knee joint shows extrusion of the medial meniscus (yellow arrow) and a ghost sign indicating posterior meniscus root tear (red arrow). (c) Standing X-ray scannogram of bilateral lower limb anteroposterior view done, showing the use of the Miniaci method to determine the correction angle of 12° (green).

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Patients not responding to conservative treatment then underwent a comprehensive work-up involving magnetic resonance imaging of the affected knee to evaluate the state of the meniscus root and presence of extrusion, and also to look at the condition of the cartilage [Figure 1b].

The alignment of the joint was evaluated using X-ray scannograms of bilateral lower limbs, and these were used to calculate the lateral distal femoral angle (LDFA) and medial proximal tibial angle (MPTA). The degree of varus at the knee joint was calculated using the Miniaci method [Figure 1c]. Patients with varus malalignment of >5° were planned for arthroscopic MMPRR along with corrective MOW-HTO.

All eligible patients were then counseled regarding the need for operative management, and informed consent was taken.

Intraoperative procedure

All patients received spinal anesthesia. The patient was positioned supine on the operating table with side support at the level of mid-thigh to stabilize the thigh and facilitate valgus positioning of the knee when required. A tourniquet was applied at the proximal thigh, and time was recorded once inflated.

Standard anterolateral and anteromedial portals were created, and a diagnostic arthroscopy was performed. Then the medial meniscus was evaluated, and the degree of extrusion was observed [Figure 2a and b]. Curette was used to clear the fibrous tissue and cartilage at the site of attachment of the medial meniscus. A trans-osseous tibial tunnel was created through the tibia. Using shuttling sutures, an all-suture anchor was pulled into the tibial tunnel just enough to reach the subchondral bone, and the hold was checked [Figure 2c]. Bites were taken through the meniscal root using a passing device. In cases with medial meniscus extrusion of more than 3 mm, meniscal centralization was done using suture anchors before final tensioning of the medial meniscus root repair. After centralization, the threads of the suture anchor securing the medial meniscus root were tied and cut once proper tensioning was ensured [Figure 2d]. The position of the root was checked, and a probe was used to confirm proper fixation.

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Figure 2: 47-year-old woman with complaints of pain and swelling of the left knee diagnosed with medial compartment osteoarthritis (Kellgren–Lawrence grade 2). Patient underwent arthroscopic meniscus repair with medial open wedge high tibial osteotomy. Intraoperative arthroscopic findings (a) medial meniscus posterior root tear was seen, with (b) extrusion of the medial meniscus. (c) suture anchors were used for fixation of the meniscus root. (d) final fixation showing centralization suture (red arrow) and meniscus root repair fixation suture (green arrow).

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The operative limb was then placed on the table in extension, and a 5 cm vertical incision was made on the anteromedial aspect, at a point between the tibial tuberosity and posterior border of the tibia, 1–2 cm below the joint line. The pes anserinus was identified and erased. The superficial medial collateral ligament was then identified and partially detached to reduce the pressure on the medial compartment. Two parallel 2 mm K-wires were passed medial to lateral from the point of attachment of the pes to the head of the fibula [Figure 3a]. A protection wire was passed vertically through the lateral condyle of the tibia to protect the hinge point. Using a Hohmann retractor to protect the posterior structures, an oscillating saw was used to make the tibial cut involving the posterior 2/3^rd of the tibia along the direction of the K-wire, keeping the lateral 1 cm of the cortex intact. Sequential osteotomes were used to widen the gap [Figure 3b]. The anterior cut was made vertically at an angle of 110° to the horizontal cut to give a biplanar osteotomy. The spreader device, along with a small amount of valgus force, was used to increase the angle to the required measurement as determined pre-operatively [Figure 3c]. Once the desired angle was obtained, the osteotomy was fixed using a locking plate [Figure 3d]. Bone graft substitute was used in cases where the correction angle was more than 10°.

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Figure 3: 47-year-old woman with complaints of pain and swelling of the left knee diagnosed with medial compartment osteoarthritis (Kellgren–Lawrence grade 2). Patient underwent arthroscopic meniscus repair with medial open wedge high-tibial osteotomy. Intraoperative fluoroscopic imaging of the left knee showing. (a) 2 parallel K-wires passed from the pes anserine insertion to the head of the fibula. (b) Osteotomy performed along the line of K-wires, keeping the lateral margin intact. (c) Using a spreader device to create the desired angle of osteotomy. (d) Fixation of osteotomy using a locked plate.

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Postoperative procedure, follow-up, and statistical analysis

Quadriceps strengthening exercises were started on the 2^nd postoperative day (POD), along with partial weight bearing with a walker. Post-operative radiographs were taken on POD-2 [Figure 4]. Brace was continued for 2 weeks postoperatively, after which knee ROM exercises were started. Weight bearing was increased as tolerated. Walker was discarded at 6 weeks post-operatively. The patient was followed up at 1 month, 3 months, 6 months, and 1 year. VAS score was recorded at 1 month. VAS, TL, IKDC scores, and ROM were recorded at 3, 6, and 12 months to look at the functional outcome of each patient. An X-ray scannogram was done at 1 year to assess mechanical alignment and union [Figure 5].

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Figure 4: 47-year-old woman with complaints of pain and swelling of the left knee diagnosed with medial compartment osteoarthritis (Kellgren–Lawrence grade 2). Patient underwent arthroscopic meniscus repair with medial open wedge high tibial osteotomy. Postoperative radiograph of the left knee, anteroposterior and lateral views, showing medial open wedge high tibial osteotomy fixed with a locking plate.

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Figure 5: 47-year-old woman with complaints of pain and swelling of the left knee diagnosed with medial compartment osteoarthritis (Kellgren–Lawrence grade 2). Patient underwent arthroscopic meniscus repair with medial open wedge high tibial osteotomy. One-year postoperative X-ray scannogram of bilateral lower limbs anteroposterior view showing union at the osteotomy site along with improvement of the mechanical alignment.

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RESULTS

Postoperative functional parameters

Patients were followed up at 1 month, 3 months, 6 months, and 12 months. One patient was lost to follow-up at 6 months.

IKDC scores ranged from 50.6 to 61.0 with a mean of 54.4 ± 3.6 at 6 months, and they improved to 67.1 ± 6.7 at 12 months (16.0 ± 6.8-point increase from preoperative value), which is clinically significant with p <0.001 and large effect size (d = 2.35) [Figure 6].

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Figure 6: (a) Graphical representation of improvement in the mean International Knee Documentation Committee (IKDC) score of all patients over time. (b) Individual patient data shows that all patients showed improvement in IKDC scores, which was clinically significant. The number after ± signifies standard deviation.

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Lysholm scores ranged from 61.0 to 79.0 with a mean of 68.0 ± 4.8 at the 6-month mark, and it increased to 79.4 ± 5.9 (17.0 ± 6.1-point increase from preoperative value) at 12 months, which is clinically significant with p < 0.001 and a large effect size (d = −2.25) [Figure 7].

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Figure 7: (a) Graphical representation of improvement in the mean Lysholm score of all patients over time. (b) Individual patient data show that all patients showed improvement in scores, which was clinically significant. Number after ± signifies standard deviation.

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VAS scores ranged from 1 to 3 with a mean of 2.3 ± 0.7 at 6 months and further reduced to 1.8 ± 0.6 at the 12-month follow-up. The mean reduction in pain scores was 1.8 ± 0.8 points from the preoperative baseline, and is clinically significant (p < 0.001 and effect size d = 2.78) [Figure 8].

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Figure 8: Graphical representation of improvement in the mean visual analog scale (VAS) score of all patients over time. Improvement in scores was clinically significant. Number after ± signifies standard deviation.

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All patients (100%) demonstrated improvement in at least one functional outcome measure, with 10 (90.9%) patients showing improvement in all three measures (IKDC, Lysholm, and VAS). No patients experienced deterioration in functional scores during the follow-up period.

No major complications were reported during the follow-up period. All patients were able to walk with support (walker or walking stick) by 1-month follow-up, with progressive improvement in mobility. Wound healing was satisfactory in all cases, with healthy wound conditions reported at follow-up visits.

DISCUSSION

OA of the knee is a condition with a large burden of disease worldwide, with India having a higher prevalence as compared to other countries at 22–30%.^[14] A high prevalence indicates that it poses a public health challenge, and various treatment modalities have been developed to address this issue. After the failure of conservative management and radical surgical procedures such as partial/total meniscectomy, the need for preservation of the meniscus was realised supported by a study conducted by Ahn et al.^[15] which showed that the MMRR group had better outcomes as compared to conservative management in patients with early OA and MMPRT in terms of functional outcome.

Meniscus repair can be performed using the transtibial suture pullout technique or using the suture anchor technique.^[16] In recent times, the concept of centralization of the extruded meniscus with the help of a suture anchor that passes through the meniscus and is fixed to the posteromedial tibia plateau has come up, and has shown promising results.^[17]

It was then proposed that a MOW-HTO, by virtue of transferring the load-bearing line laterally, helps offload the medial compartment by reducing the stress on the medial condylar cartilage and supports the meniscus repair.^[18,19] Some studies,^[20] including cadaveric studies^[21] exhibit good functional outcomes as well as improved healing of the meniscus on second-look arthroscopy. There is evidence to believe that surgical repair of a meniscus root tear with MOW-HTO may even delay the need for a total knee replacement^[22] with post-HTO joint survival rates ranging from 88.6–96.1% at 5 years to 45–68% at 15 years.^[23]

Literature in this area is continually evolving with newer studies questioning the benefits of MMRR with MOW-HTO as compared to HTO alone, with short-term studies showing limited benefit of MMRR while highlighting the need for long-term follow-up.^[20] On the other hand, some studies downplay the role of HTO in the management of MMPRT, suggesting no additional usefulness of this procedure.^[24]

All of the above serve to show that knowledge in this area is limited, with no consensus on the ideal management protocol in patients with early OA and MMPRT. This drives the need for further research, especially in an Indian setting due to the higher prevalence of this condition in the region, along with a lack of available insight.

In our study, we found a significant (p < 0.05) improvement in the functional outcome based on IKDC, Lysholm, and VAS scores in patients with early OA and MMPRT who underwent MMRR and MOW-HTO. The improvement in outcome was sustained over a period of 12 months, and no patient showed any deterioration in knee function after the procedure. No patient had any long-term complications such as neurovascular injury, non-union of osteotomy site, mechanical failure of meniscus repair, hemarthrosis, or arthrofibrosis.

This study has some limitations, including the small sample size (n = 11) from a single center, lack of a control group, and relatively short follow-up period (12 months). The study population was heterogeneous in terms of age, BMI, and activity levels, which may affect the generalizability of results.

This study demonstrates that combining arthroscopic MMPRR with MOW-HTO yields significant improvements in functional outcomes at 12 months in middle-aged Indian patients with early OA and varus malalignment. These findings are particularly relevant in India, where knee OA prevalence is high, yet data on meniscus root tears and optimal surgical strategies remain scarce. By highlighting the diagnostic pathway, surgical technique, and demonstrating good outcomes without major complications, this paper aids clinicians in patient selection for combined procedures to preserve the native joint while providing clinical benefit.

Larger multicentric studies are required in this area, involving more patients and a longer follow-up period (>5 years) to give clearer recommendations regarding the use of the combined approach (MMPRR and MOWHTO) versus HTO alone. A long-term follow-up will also allow second-look arthroscopy and assessment of objective parameters such as survival of repair and cartilage status. Matching cohorts with respect to age, BMI, and severity of disease will improve generalizability.

CONCLUSION

Medial meniscus root tear should be suspected in middle-aged patients who develop sudden-onset knee pain without any inciting injury. After appropriate radiological investigation, a decision to perform a meniscus-saving procedure can be taken, provided the patient meets the necessary prerequisites, as patient selection is vital to achieve good results. This study shows significant functional improvement in patients who have an MMPRT and have been managed with arthroscopic MMRR along with MOW-HTO. All the patients showed improvement in functional parameters, and no major complications were reported at 1 year postoperatively. None of the patients has shown any deterioration in knee function after surgery. More studies are needed in this area with larger study populations and multicentric trials to provide clearer results that can aid decision-making.

Author contributions: PS, UR: Concept, design, definition of intellectual content, data analysis, manuscript editing review; UR and LK: Literature search; UR, PS, AY, AJ: Clinical study, patient diagnosis, planning and follow-up, PS and UR: Surgical intervention; UR, LK, AY: Data collection, statistical analysis; UR, AY, AJ, LK: Manuscript preparation; UR and PS: Guarantors (take responsibility for the integrity of the work as a whole from inception to published article).